GIFT OF

Samuel G. Clark

SCIENCES LIBRARY

EARTH

'i

OF

DETERMINATIVE

MINERALOGY

WITH AN INTRODUCTION ON

BLOWPIPE ANALYSIS.
BY

GEORGE

J.

BRUSH,

Late Director of the Sheffield Scientific School of Yale University,

REVISED AND ENLARGED, WITH ENTIRELY NEW TABLES FOR THE IDENTIFICATION OF MINERALS,
BY

SAMUEL

L.

PENFIELD,

Late Professor of Mineralogy in the Sheffield Scientific School of Yale University.

SIXTEENTH EDITION, REVISED.

TOTAL ISSUE, TWELVE THOUSAND

NEW YORK JOHN WILEY & SONS,

LONDON:

INC.

CHAPMAN &
1914

HALL, LIMITED

EARTH SCIENCES LIBRARY

COPYRIGHT, BY

1898,

SAMUEL

L.

PENFIELD.

GPOLOGICAL SCIENCES

THE SCIENTIFIC PRESS ERT DRUMMOND AND COMPANY

BROOKLYN,

N. Y.

PREFACE.
a complete revision of the " Manual of Determinative Mineralogy and Blowpipe Analysis" by Prof. Geo. J. Brush, which has been very generally used since its first appearance in 1874, as shown by the fact that fourteen editions of it have appeared. In 1896 a revision of the introductory chapters devoted to blowpipe analysis and the chemical reactions of the elements was published, and there are now added a chapter on the physical properties of minerals, devoted chiefly to crystallography, and a new set of analytical tables for the identification of minerals. In preparing the introductory chapters, great pains has been taken in the selection of the tests for the elements. Many of the experiments are performed by means of the blowpipe, but chemical tests in the wet way are recommended when it is believed that they are more decisive. All the tests have been carefully verified, and many of them have been devised especially for the present work. To make the book more convenient for reference, conspicuous headlines and catch-words have been freely used. The tests for the rare elements, and those for the common ones which are only occasionally employed, are printed in small type. It is hoped that the plan adopted of giving full directions concerning the methods of manipulation and the quantities of materials to be taken in making many of the tests will be found useful. It must be borne in mind constantly that accuracy is of the utmost importance in determinative mineralogy, and it is believed that no methods are so generally to be relied upon for giving decisive results as those based upon the identification of the chemical constituents of the minerals. Moreover, most minerals can be iden-

THE

present

work

is

tified by means of very simple tests, although some cannot be determined beyond question without resorting to the more elabiii

GB55794

IV

PREFACE.

orate methods of quantitative chemical analysis, or an exact determination of their crystalline form.

The chapter on the physical properties of minerals is a new feature of the book which it is believed will add to its usefulness. The endeavor has been made to present the important subject of crystallography as simply as possible. Importance has been attached to the description of those forms which are most frequent in their occurrence, and, with few exceptions, the examples chosen to illustrate the different systems represent the development of the
simple forms which prevail on specimens of common minerals. Hare and complex forms have been treated very briefly, and theoretical considerations have been left largely to the more elaborate treatises on crystallography. In describing the physical properties of crystals the idea has constantly been kept in mind that the book is to be used for the identification of minerals, and, consequently, only those methods are included which are especially important as a means for identification. Optical methods have been omitted because they would increase the size of the volume to too great an extent, and, except as they are accompanied by accurate descriptions of the crystal forms, their application is limited. The analytical tables for the identification of minerals are an outgrowth of the tables of von Kobell as modified by Professor The introduction, however, of a large number of new Brush. species since 1874 has necessitated a complete rearrangement of the minerals. The tables have been so developed that tests for characteristic chemical constituents furnish the chief means for identification. Thus, in identifying minerals, students may gain of important information concerning the chemical compossession position of the compounds. The distribution of the minerals in the tables, and statements concerning their chemical and blowpipe characters, have been verified in almost all cases by experiments made upon well-authenticated specimens in the Brush collection at New Haven. In some cases, however, it has not been possible to locate rare minerals with certainty in the places where they properly belong, because the original descriptions have not been suffiThe author would be pleased to receive any ciently complete. information concerning the properties of minerals which could be incorporated in future editions, and thus render the tables more complete and accurate. The tables are intended to include all of the well-characterized mineral species known at the present time, and although nearly eight hundred species have been included, it is

PREFACE.

believed that they are adapted to the use of beginners who desire especially to become acquainted with the common minerals. In order to accomplish this end the common minerals are printed conspicuously in capitals, and thus on opening any page of the tables they may be recognized at once by glancing down the column " Name of Species." The author takes pleasure in expressing his obligations to his associates, Professors G. J. Brush, E. S. Dana, L. V. Pirsson, and H. L. Wells, for many valuable suggestions, and to the Misses L. P. and K. J. Bush of New Haven for services rendered in the

preparation of the manuscript and in proof-reading. The woodcuts were prepared by the skillful engraver, Mr. W. F. Hopson of

New

Haven.
October
1,

NEW HAVEN,

1898.

PREFACES OF THE FORMER EDITIONS OF THIS WORK,

BY GEORGE

J.

BRUSH.

PREFACE TO THE FIRST EDITION.

THE

material in this compilation was, far the greater part,

and myself,

prepared almost twenty years since, by Prof. S. W. Johnson as a text-book for the students in our laboratory. Circumstances prevented its publication at that time, but it has

served as the basis of a course of lectures and practical exercises

annually given in the Sheffield Laboratory. The plan of instruction has been to have the student work

through a course of Qualitative Blowpipe Analysis as introducFor the latter subject, we tory to Determinative Mineralogy. have employed VON KOBELL'S Tafeln zur Bestimmung der Mineralien,

many of the students taking the work in the original, while others made use of either Erni's or Elderhorst's translations.
self

These

"

Tables

"

were translated by Prof. Johnson and my-

while

we were

Munich, and it horst, that he introduced von Kobell's "Tables" into the second edition of his " Manual," although he did not avail himself of our translation, which was then offered to him for that purpose.
T!

students of Prof, von Kobell in 1853-4, at was after our suggestion, in 1860, to Prof. Elder-

PREFACE TO THE FIRST

EDITION".

vii

The German

presented are based on the tenth edition of von Kobell's book. Additions of new species

"

Tables

"

as

now

have been made, and in many cases, fuller details are given in regard to old species, and the whole material has been thrown into
an entirely new shape, which it is believed will greatly facilitate the work of the student. The preparation of the tables in this
form, the idea of which was suggested to me by Prof. ROEPPER, has been performed, under my supervision, by
sistant,

W. my

T.
as-

Mr. GEORGE

W. HAWES, who
work, and

has also aided

me

greatly in

revising the rest of the

sheets.

in the reading of the proof-

authorities used in the original preparation and later revision of the chapters on Blowpipe Analysis were the

The main

works of BERZELIUS and PLATTNER.

The

third and fourth edi-

tions of Plattner, the latter edited by Prof. RICHTER, have been chiefly consulted. The complete work of Plattner, with still later additions by Prof. Richter, has been made accessible to English-

reading students through an excellent translation by Prof. H. B. CORNWALL, and this cannot be too highly commended to those

who
ject.

desire to

become

fully acquainted with this important sub-

In Determinative Mineralogy, besides the works of von Kobell, free use has been made of the treatises of NAUMANN and
especially of the pyrognostic characters contributed by myself to the latter work. This constitutes, in accordance with the original plan of Professor Dana and myself, the Determina-

DANA,

tive Part of his

future time to
of minerals

System of Mineralogy. It is proposed at some add to the volume methods for the determination
their physical characters.

by

In conclusion, I take great pleasure in acknowledging my indebtedness to my colleague, Prof. S. W. Johnson, who has not only generously given me his share in the original work, but ha$ constantly aided me by his advice in the revision here presented.
SHEFFIELD LABORATORY OF YALE COLLEGE, HAVEN- December 15, 1874.

PREFACE TO THE THIRD AND LATER EDITIONS.

THIS edition has been so far revised as to substitute for the old formulas for minerals, those based upon the atomic weights
of the elements adopted by the so-called new chemistry. The formulas for the most part have been taken from Rammelsberg '$

Mineralchemie (Leipzig, 1875), and are made to correspond as far as possible with those given in Dr. E. 8. Dana's Text -Book
Sons, New York, 1877). of Mineralogy (John Wiley It should be stated here that as the main object of this
is

&

book

the identification of mineral species by a method largely based on the blowpipe characters of their elemental constituents, this

Instead point has been kept in view in writing their formulas. of giving a symbol for a group of elements, as is usual in mineralogical treatises, it has been necessary to give the elements in full, and in some instances, for want of space, a simple list of the constituents is substituted for the formulas. This has also

been done in the case of minerals where no satisfactory formulas have been deduced. It has not been thought advisable to alter the old common names used for reagents and compounds, since the book is intended not only for students in colleges and schools, but for all the
different classes of persons minerals.

who

are interested in the study of

in the text of the tables are

A
My

few changes and additions

it is

trusted, will facilitate the work of the student. made, which, acknowledgments are again due to Mr. George W. Hawes

for his cooperation in

making these changes.

viii

NEW

HAVEN, May

1,

1878.

TABLE OF CONTENTS.
CHAPTER
The Mineral Kingdom: Minerals
Rocks: Chemistry
I.

PAOB

INTRODUCTION AND CHEMICAL PRINCIPLES.

1

CHAPTER

II.

APPARATUS AND REAGENTS, AND CHEMICAL PRINCIPLES VOLVED IN THEIR USE.

Apparatus Dry Reagents Gaseous Reagents Wet Reagents The Nature and Use of Flames
;

IN10 24 27
31

CHAPTER
REACTIONS OF THE ELEMENTS.
Aluminium
Other Elements follow
in

IIL

42
Alphabetical Order.

CHAPTER

IV.

TABULATED ARRANGEMENT OF THE MORE IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

Heating in the Platinum-pointed Forceps Flame Coloration Heating in the Closed Tube Heating in the Open Tube Heating on Charcoal Treatment with Cobalt Nitrate Fusion with the Fluxes on Platinum Wire Treatment with Acids, and Reactions with the Common Elements
:

135 137
140
142 146 147
151
iz

TABLE OF CONTENTS.

CHAPTER
PHYSICAL PROPERTIES OF MINERALS.
Crystallography Structure of Minerals

V.
PAGB

155
221

Cohesion Relations of Minerals

Properties depending
Properties depending

upon Light
upon Weight
:

Properties depending upon Heat

Specific Gravity

223 227 230 232

CHAPTER

VI.

TABLES FOR THE DETERMINATION OF MINERAL SPECIES BY MEANS OF SIMPLE CHEMICAL EXPERIMENTS IN THE WET AND DRY WAY AND BY THEIR PHYSICAL PROPERTIES.
Introduction to the Tables
Analytical Table for the Identification of Minerals
:

General Classification..

239 245 246

Tables

INDEX TO SUBJECT-MATTER INDEX TO MINERALS..

303
307

DETEEMINATIVE MINERALOGY AND BLOWPIPE

ANALYSIS,

CHAPTER

I.

INTRODUCTION AND CHEMICAL PRINCIPLES.

Natural products are commonly divided into three kingdoms, animal, vegetable, and mineral.

The Mineral Kingdom.

The

latter includes those substances constituting or

found in the
of
life.

crust of the earth

and not those made through the agency

frequently
called

They

are,

therefore,

inorganic

materials.

Among

these,

two
? ocTcs.

classes are recognized,

which are known as

minerals and
Minerals.

These are definite chemical compounds occurring

in the mineral kingdom.

The following may serve

as examples :

Pyrite, sulphide of iron, FeS,.

Quartz, oxide of silicon, SiO,.

Orthoclase, silicate of potassium

and aluminium, KAlSi,0 8

.of

Chemical formulae show the invariable composition

minerals

the

pure, that of quartz, for example, indicating that 1 atom of silicon is in combination with 2 atoms of oxygen. It

when

ought to be possible to express the composition of every mineral by a chemical formula, but there are some for which this cannot
yet be done, owing to the fact that they have not been sufficiently
investigated.

On examining minerals, it will be observed that they usually occur in definite geometrical shapes called crystals, when conditions favorable for the formation of crystals have prevailed.

INTRODUCTION AND CHEMICAL PRINCIPLES.

Every distinct chemical compound occurring in inorganic nature, having a definite molecular structure or system of crystallization and well-defined physical properties, constitutes a mineral species. Up to the present time, between eight and nine hundred minerals, which deserve to rank as distinct species, have been recognized. Of these, however, only a few can be considered as common, and
really important either as rock-forming minerals in

making up the

crust of the earth, or as ores of the useful metals, or as otherwise valuable in the arts. Each mineral species has received a name

(usually ending in

'

ite,

signifying

of the nature ofj 'UJce^ by

which it is commonly known. In assigning these names no system has been followed, some being derived from chemical, physical, or fanciful peculiarities, some from localities where the minerals were first found, while many are named after persons.
the exception of a few glassy lavas, rocks are aggregates of mineral particles. The term rock is often used in a general way for designating any portion of the earth's crust, but

Rocks.

With

the kinds of rock to which geologists have assigned special names contain certain minerals in about the same proportion throughout.

Thus, granite

is

examination, a fragment of
different minerals.

one of the commonest rocks of the globe, and, on it will be found to be made up of

The most conspicuous

is

orthoclase,

p, 9 together with a corresponding soda mineral, albite, and quartz, SiO,, while a number of others may be present in small amounts. The proportion of these minerals differs in differ-

KAlSi O NaAlSi O
3

s,

ent kinds of granite, and

it is

therefore evident that the composition

of this rock cannot be expressed

by a

definite chemical formula.

In a rock, the structure may be coarse-grained, so that the particles can be detected with the naked eye, or fine-grained, rendering a microscope necessary to distinguish the different components. Usually a rock is composed of different minerals, but
it

sometimes consists of only one.

Thus, marble

is

an aggregate

of particles of

calcite, s quartzite of quartz, SiO,. The study of rocks, known as lithology or petrography, necessitates a
,

CaCO and

previous knowledge of mineralogy.

INTRODUCTION AND CHEMICAL PRINCIPLES.

Chemistry.

Mineralogy

is chiefly

proper understanding of minerals, chemistry

is

indispensable.

a chemical science, and for a some knowledge of elementary brief summary, therefore, of some

important chemical principles will be first given. By a careful study of the experimental part of the following chapters, it is believed that much useful information concerning general elementbe gained. A substance which cannot be separated into simconstituents is regarded as an element. At the present time, pler about 70 elements are recognized. Of these, less than half are

ary chemistry Elements.

may

occurrence, while, from a consideration of a large number of rock analyses, F. W. Clarke * has calculated that 99 per cent of the solid crust of the earth, for a depth of ten miles, is
of

common

composed

of the following eight elements

Oxygen,
Silicon,

47. 3#

Calcium,

3.8#

27.2
7.8 5.4

Aluminium,
Iron,

Magnesium, 2.7 2.4 Sodium,

Potassium,
2.4

Atoms, and Molecules. Elements manifest This property is known as tendencies to unite with one another.
Chemical
Affinity,

It is usually strongest between metallic and chemical affinity. non-metallic elements as sodium and chlorine in sodium chloride.
,

The smallest
is called

particle of an element

which enters into combination

which

is

an atom, and the smallest particle of a chemical compound capable of existence is called a molecule.

For convenience, elements are designated by symthe initial letter of their names, or this with one other bols, usually Each symbol stands for one atom of the element as S for letter.
Symbols.
;

sulphur,

Pb

for lead (Latin,

plumbum).
of,

PbS

is

the chemical for-

mula

of,

and represents a molecule

of Definite Proportion.

Law
definite,

lead sulphide. Atoms unite with one another in

different, proportions.

though frequently in two or more

*Phil. Soc. of Washington, Bull. IX., p. 138, 1889.

INTRODUCTION AND CHEMICAL PRINCIPLES.

For example, carbon, sulphur, and arsenic, each form two distinct oxides, CO and CO SO, and SO,, As O and As O Valence. This term is used to express the numerical proportion in which elements unite with or replace hydrogen. Chlorine is univalent and oxygen bivalent, because they unite with hydrogen to form the molecules HC1 and H O, respectively. The term
2
,

6.

valence

H S0
a

4 ,

is also applied to compounds. Thus, sulphuric acid being the radical S0 4 is said to be bivalent.

Acids.

Compounds

resulting from the union of non-metallic

elements, with hydrogen or hydrogen and oxygen, in which the hydrogen atoms may be replaced by metals, are called
acids.

These usually possess a sharp, sour taste and have the

property of turning blue litmus-paper red.

;

The common mineral3 ;

hydrofluoric, forming acids are hydrochloric, HC1 nitric, HN0 HF hydrogen sulphide, Ha S sulphuric, H SO carbonic, H CO
; ;

4 ;

3;

boric,

H,B0
4 ;

8 ;

phosphoric,

H P0
3 6
,

H Si0
4

metasilicic,

H Si
4

H As0 and polysilicic, H Si O

4 .;

arsenic,

4 ;
8.

orthosilicic,

In the fore-

going formulae, the groups of elements with which the hydrogen atoms are united are often called acid radicals. Thus, S0 4 is the
acid radical of sulphuric acid
silicic, etc.
;

PO

of phosphoric

Si0 of ortho4

Combinations of metals with oxygen and hydrogen (the hydroxides; for example, NaOH, sodium hydroxide) are called bases. These have the property of neutralizing acids, and,
Bases.
.

if

soluble in water, of turning red litmus-paper blue. The combinations of metals with oxygen are sometimes called basic

oxides.
of acids and and resulting in the replacement of part or all of the hydrobases, gen atoms of the acid by metals, are called salts. The great majority of minerals are salts, and in a natural chemical classificaSalts.

Compounds formed by the combination

tion they are subdivided into groups according to the acid radicals which they contain i.e., the sulphides, salts of hydrogen
;

sulphide, in one group the sulphates, salts of sulphuric acid, in another the silicates, salts of silicic acid, in a third, etc.
;
;

INTRODUCTION AND CHEMICAL PRINCIPLES.

a knowledge of the valence of a given metal, it is a simple matter to write the normal salt of any known acid, as shown by the following table
:

With

Hydrochloric,

Sulphuric,

HC1.

H S0
a

Phosphoric,

Orthosilicic,

4.

H,P0 4

Si0 4
4

Sodium, Na, univalent,

Calcium, Ca, bivalent,
Ferric iron, Fe, trivdlent,

NaCl
CaCl, FeCl s

Na a SO 4
Ca*SO,

NasPO, Ca 3 (PO 4 ) a

Na

SiO 4 Ca 2 SiO 4

Fe 2 (SO 4 ) s

FePO 4

Fe 4 (SiO 4 )f

Chemical Equations. When chemical substances react upon or unite with one another, definite transformations take place,

which can be expressed in the form of equations.

Thus,

when
with

calcite is dissolved in hydrochloric acid, or barite is fused

sodium carbonate, the

results are

shown
a

as follows

CaCO,

BaS0
The

+ 2HC1 = CaCl + H O + CO,. + Na CO, = BaC0 + S0

a a
3

]STa a

4.

pose in affording a

practice of writing correct equations serves a useful purknowledge of the manner in which chemical

reactions take place.

Atomic Weight.

It

has been found that an atom of an

element possesses a definite relative weight, known as its atomic weight. This is based on an atom of hydrogen, the lightest of all
elements, as a standard (the weight of the hydrogen atom being taken as 1). The atomic weights of the common elements have

been very accurately determined and are generally given with

their descriptions.

Molecular Weight. The molecular weight of a substance is equal to the sum of the atomic weights of the elements constituting
Thus, calcium, carbon, and oxygen, having the atomic weights 40, 12, and 16, respectively, CaCO 3 has a molecular 48 = 100. 12 weight of 40 Relations between Chemical Formulae and Percentage Con position. With a knowledge of the chemical formula of a corn
the molecule.

pound and
of the

of the atomic weights, the percentage composition

different

constituents
is

example, sphalerite

ZnS.

For can be readily calculated. = 65.4 and The atomic weights are Zn

INTRODUCTION AND .CHEMICAL PRINCIPLES.

is 97.4. In 97.4 parts of ZnS there are 65.4 parts of zinc, consequently the by weight zinc in 100 parts may be readily calculated by a simple proportion,

32,

hence the molecular weight of ZnS

67.1 as the per cent of zinc. convenient to give the percentages of combinations of the elements, especially the oxides, instead of the elements themselves. This is illustrated by the following examples, where the
:
:

thus

97.4

65.4

= 100

a?,

which gives

It is often

percentages are derived from the molecular weights by the proportion, Total Mol. Wt. Mol. Wt. of constituent = 100 x:
:

Andradite Garnet.

Dolomite.
.

Ca 3 Fe a Si 3 Oi 2
At.Wt.

3CaO.Fe 2 O 3 .3SiO a
Mol.Wt.
Si
,,

CaMg(CO

3)2

= CaCO

.MgCO 3

At.Wt. Mol.Wt.

O;,
,

28 82

X3 = 18
|
)

"

85 4*
'

Fe 2 112
O,,

48
16

1Rn 16
1ftft x o =168 3 168

Fea n " a

Q1 5 31
'

O" O
3
,

M
48 24 \t \t\ 48 J

100

CaCO,,

54.3*

Mg,
QO 1 S3
., -

Ca,

40)
\

O,

p n Ca0

'

C, O,,

_
84

MgC0

45.7

508

100.0

184

100.0

Quantitative Chemical Analyses. The chemical composition of minerals is determined by means of quantitative analyses, and many of these will be found recorded in the larger treatises

on mineralogy.

a percentage analysis gives the weights of the different constituents in one hundred parts, and each constituent has its definite relative weight (atomic or molec-

Now,

since

ular), therefore the relative

number

of atoms or molecules

may

be

found by dividing the percentages by

weights.

their atomic or molecular-

The quotients indicate the

ratio of the constituents,

which is usually a simple one. The following examples of actual analyses

Sphalerite. Found. At.Wt.
S,

will illustrate this

Andradite Garnet.
Ratio.

Found.

Mol.Wt. Ratio.

32. 93

-f-*-

32
65.4

=1.029

Zn, 66.69
Fe,
.42

SiOt,
,

35.44-5-*-

60

1.019

Fe 2 O 3 31.85
CaO,

160
56

MgO,
100.04

_
100.34

32.85 H.20

= .591 = .199 = .587

INTRODUCTION AND CHEMICAL PRINCIPLES.

7
:

The
:

ratios derived

from these analyses are as follows

S Zn

= 1.029
2
:

1.019

= 1.00
.591
:

0.99, or
:

very nearly 1
:

1.

SiO

Fe O, CaO

.199

.587

= 2.95

1.00

2.97, or

nearly

3:1:3.

The formula of sphalerite is, therefore, ZnS, and that of the or Ca Fe Si O These analyses may garnet, 3CaO.Fe O .3SiO
2
3

12 .

be compared with the theoretical values calculated in the previous

paragraphs.

Substances which Isomorphism (firos, equal, yuop0^, form). are analogous in chemical composition frequently show a simiThis is known as isomorphism. Thus, larity in crystallization.
the alums,

morphous.

KAl(S0 ) .12H O, and (NH )Al(S0 ) .12H O, are isoThey must have similarity in molecular arrangement,
4

for they not only crystallize in the

tion containing both salts,

same shapes, but, from a solua crystal may be grown consisting

partly of potash and partly of

ammonia alum.

This tendency of
proof of

two

salts to crystallize together constitutes the strongest

their isomorphism.

Isomorphism plays a very important part in mineralogy. Many species are mixtures of two or more isomorphous chemical
molecules, and, owing to this fact, the physical properties (especially color, specific gravity, and fusibility) are often found to

vary widely.
tion

For example, sphalerite when

colorless or nearly so.

it

has the composihowever, contains

ZnS

is

It usually,

isomorphous FeS, and the color becomes darker as the percentage of iron sulphide increases. Columbite, FaN"b O, and the isomorhave the specific gravities 5.3 and 8.2, phous tantalite, FeTa O respectively while intermediate mixtures of the two molecules have specific gravities ranging between these values.
a
,

Concerning isomorphous mixtures, it is often stated that one element replaces the other; i.e., sphalerite is ZnS, but part of the

To express the composition of these mixed compounds, two methods are commonly employed either the isomorphous elements are designated by some symbol,
zinc

may

be replaced by iron.

INTRODUCTION AND CHEMICAL PRINCIPLES.

as R, or they are enclosed in parentheses.
ite is

For example, sphalersaid to have the composition RS, where R = Zn and Fe, or

(Zn,Fe)S, giving importance to the prevailing constituent

by

plac-

ing

formula,

often, also, by using larger type. not meant that sphalerite contains one atom of zinc, one of iron, and one of sulphur, but that the zinc and iron taken together are equivalent to one atom of a bivalent metal.
it first,

and

By

the latter

it is

The following examples will illustrate the methods formulae from analyses of isomorphous compounds
:

of deriving

II.

III.

Brown

Sphalerite.
Ratio.

Roxbuiy, Conn.
Found. At.Wt.
S,

Black Sphalerite. Felsobanya.

Found.
S,

Almandine Garnet. Fort Wrangel, Alaska.

Found.
Mol.VVt.
-T-

At.Wt.

Ratio.

Ratio.

33.36

-T-

32

=1.043

33.25-i-t-

32
65.4

=1.039

SiO a

39.29

60

.655

Zn, 63.36-^65.4 3.60 -h 56 Fe,

100.32

= =

.969

.064

Zn, 50.02 Fe, 15.44

-H
-5-

56
112

Cd,
Pb,

.30

1.01 * 207

= = = =

756

100.02

INTRODUCTION AND CHEMICAL PRINCIPLES.

ent crystalline forms, are said to be dimorphous. Thus, carbon crystallizes in the isometric system as diamond, which is hard and
transparent, with specific gravity 3.52; and in the hexagonal as graphite, which is soft and opaque, with Sp. Gr. 2.15. system

Calcium carbonate, CaCO

Sp. Gr.

= 2.71,
it is

is calcite

crystallized in the hexagonal system, and in the orthorhombic system, Sp. Gr.
,

2.94,

aragonita

Iron sulphide,

isometric system, Sp. Gr.

= 5.02,
=

is

FeS crystallized in the pyrite, and in the orthorhomQ

,

bic system, Sp. Gr. Titanic oxide, Ti0 2 4.90, it is marcasite. crystallizes in two entirely independent modifications in the
,

tetragonal system, with Sp. Gr. 4.20, as ru tile, and with Sp. Gr. ~3.90, as octahedrite, and also in the orthorhombic system,
Sp. Gr. =4.0, as brookite.

The

last case,
is

where three independ-

ent modifications of TiO 2 occur,

Dimorphism and trimorphism may the number of atoms, to variations

an example of trimorpliism. be due either to variations in

in the arrangement of the

latter in the chemical molecule, or to variations in the arrange-

ment of the particles in the structure of the crystal. No exact means for determining the size of the chemical molecule in solid for example, is the simple substances exists at present. TiO
2
,

empirical formula for rutile, but

its

true composition

is

undoubt-

edly some multiple

of

TiO a

CHAPTER
THEIR USE.

II.

APPARATUS AND REAGENTS, AND THE PRINCIPLES INVOLVED IN

PART

1.

APPARATUS.

Although a great deal of blowpipe apparatus has been devised, only that will be described in the present work which is necessary
or convenient for

making the simple

tests for the identification of

the elements and the determination of minerals.

In performing

most of the experiments a simple and inexpensive outfit will suffice, which, if necessary, can be packed in small space, so as to
be portable.
Moreover, a
little

ingenuity will often enable one to

supply the place of

much

The Mouth- Blowpipe.

apparatus. This instrument, for centuries em-

ployed only by artisans in soldering and in other operations requiring an intense heat, has been for a period of considerably over one hundred years an invaluable means of scientific research.*
It is of the greatest service to the mineralogist

and chemist for

the identification of minerals and the detection of their ingredients, and may even be used for the quantitative separation of several

metals from their ores.f

Anwendung

* For a brief history of the use of the blowpipe, see Berzelius's work, Die des Lothrohrs; or the translation by J. D. Whitney, Boston, 1845.

more complete history is found in Kopp's Geschichte der Chemie, II, p. 44, Braunschweig, 1844, and also in von Kobell's Geschichte der Mineralogie,
Miinchen, 1864.
t Quantitative

interested in Plattner's
nickel, iron, etc.,

blowpipe analysis is beyond the scope of the present work. Those methods of assaying ores of gold, silver, copper, lead, cobalt, by means of the blowpipe, are referred to his work, Probirkunsi
edition,

wit dem Lothrohre; German H. B. Cornwall.

by Th. Richter; American translation, by

10

APPARATUS.

11

With no

other fuel than that furnished

by a common lamp

or

candle, the blowpipe renders it possible to produce in a moment a most intense heat. In the blowpipe flame, not only are many refractory bodies melted or volatilized, but entirely opposite

chemical

effects,

oxidation and

Almost

all

chemical substances

reduction, jnay be produced. may be made to manifest some

phenomena under its influence, either alone or in the of certain other substances known as reagents, and thus presence their nature may be detected.
characteristic

The blowpipe is represented in its usual form in Fig. 1. The parts a and b fit into the chamber c with ground joints. Any moisture from the breath which condenses in a collects in c, and may be removed by disjointing the parts. The instrument is also furnished with a tip or jet (the most important part), which fits on b by means of a ground joint, and is shown at d in correct proportion and twice the natural size. The hole at the end of the tip should be slightly tapering and from
0.4 to 0.6

mm.

in diameter.

It
its

should be
axis is in

bored in such a manner that

line

with the axis of the tube b when the

parts are fitted together. Very durable and inexpensive tips are made of brass. Those

bored and turned out from solid platinum are expensive and scarcely better than brass,
while light ones spun from platinum
unsatisfactory.
foil are

Tips are very apt to become with dust or foreign matter, and stopped new ones often contain bits of metal turn-

FIG.

1.

ings, or need to be reamed out to the proper size and taper. Cleaning and adjusting can best be accomplished by means of

a four-sided, slightly tapering reamer, which may be filing down the sides of a large steel needle or pin.

made by
For the

successful working of the blowpipe, it is also important that the

12

APPARATUS.

hole through b should not be eccentric, and that there should be nothing to disturb the passage of air.

The instrument as shown

mouthpiece,
is

in Fig.

of the original

but without the trumpet form proposed in the last century

1,

by Gahn, and employed by

apt to result in is required to using it, keep the lips closed about the tube for any length of time. Fig. 1 represents the blowpipe provided with the trumpet

Berzelius.

Fatigue

is

as considerable effort

mouthpiece,

e,

recommended by

Plattner.

This

is

made

of horn

or hard rubber, 35

mm.

in its outer diameter,

and should have

such a curvature that, when placed against the lips, it does not give an unnecessary or unequal pressure. A very good mouthpiece may be made from a piece of glass tubing 5 cm. long, and of suteh diameter as fits the blowpipe tube.
It

should

first

be strongly heated for half

soft flattened

its

length in the flame

of a lamp,

and when quite

between two smooth me-

tallic surfaces, to give.it

the form shown in Fig. 2. The other end should then be cemented into the blowpipe by means of sealing-wax., This kind of mouthpiece, when inserted
lips,

between the

displaces

them but

slightly

from their
. .

customary position,

and causes very

little fatigue.

FIG.

2.

The blowpipe is usually made of brass, or preferably of German silver: The length of the instrument should be measured by the visual distance of the operator, the ordinar y length being from 20 to 22 cm., exclusive of the
artisan's blowpipe, Fig.
3,

mouthpiece.

The common, and curved tube

small needle.

consists of a tapering

of brass, terminating in an orifice as large as a

well constructed, this simple instrument answers most purposes, and is often made without the bulb
is

When

near the bend, which ing from the breath.

intended to collect the moisture condens-

great deal of

different

ingenuity has been expended in devising forms of blowpipes and mouthpieces, each supposed to

have some special feature either of excellence or of cheapness to

APPARATUS.

13

recommend

the blowpipe has a good tip, the form is of little importance, provided the operator is skilful and has become accustomed to the use of his init.

However,

if

strument.

Blowing. In blowpipe operations it is often necessary to maintain an uninterrupted stream of air for
several successive minutes.

To be able

to

do

this easily

requires some practice. It is best learned by fully distending the cheeks, closing the communication between

the mouth-cavity and windpipe by means of the palate, and breathing through the nose. When one is accusto keeping the cheeks thus inflated, the mouthpiece of the blowpipe may be pressed against or inserted

tomed

between the
distended.

lips,

attempting to

and the same thing repeated without blow or do more than keep the cheeks
operator, continuous

To the experienced

blowing is hardly an effort.* Fuel and Lamps. The most convenient combustible is ordinary illuminating-gas burned in a Bunsen burner,
Fig.
4.

FIG.

3.

The gas

issues

from a small

orifice

near the lower end of the tube, and mixes with a large proportion of air which enters

through holes at 7i. Usually the lamp is provided with a ring at ^, fitting loosely
over d, and by turning this the supply of air can be varied. The mixture of gas and air

should be so regulated that the burner gives a non-luminous, blue flame, with a distinctly outlined inner cone about 5 cm. high.
FlG 4
*

For use with the blowpipe, an additional

Various mechanical contrivances have been devised where the air is supplied from bellows, but they are regarded as unnecessary. The strength of the blast needs to be often varied in order to bring about different effects, and with the breath this can be most readily accomplished. Only students showing enterprise and patience
sufficient to

master the use of ordinary instruments

will

be likely to

make much

progress in blowpipe analysis.

APPARATUS.
tube,

supplied, which fits loosely inside of d, and goes down below the holes at 7^, thus cutting off the supply of air, and
e, is

causing the gas to burn with a luminous flame. The tube is flattened at the top, and one side is made a little lower than the
other, so that the blowpipe flame can be directed

downward when

necessary. slightly raised notch at the upper side serves as a rest for the blowpipe tip. burner like the one shown in Fig. 5 is con-

it gives only a luminous flame it not suitable for heating glass tubes, etc., and an additional Bunsen burner is necessary.

venient, but as
is

gas is not at hand, olive- or rape-oil, burned in a lamp with a rectangular wick, 5 X 10 mm. in diameter, may be used. Fig. 6 represents
the
FlG. 5.

When

form of lamp proposed by Berzelius and

improved by Plattner. The openings for the wick and for the admission of oil are provided with close-fitting screw-caps, and the apparatus
can be taken apart and packed in small space for transportation.
Fig. 7 represents a

by

the

Buffalo Dental

lamp made Manu-

facturing Co., which gives satisfactory results. form of lamp adapted for

portable blowpipe apparatus is represented in Fig. 8. Paraffin is

used as

fuel,

and must be melted

before lighting, but, when once ignited, the heat from the flame

keep a sufficient quantity of the paraffin in a liquid condition. When more convenient material
will

FIG.
is

6.

quality will

not at hand, candles of good answer for most purposes. A large candle with a flat
easily

wick can be

made, and

is

some improvement on the ordinary

APPARATUS.

15

form.
it is

For heating glass tubes, boiling liquids in test-tubes, etc., desirable to have a flame which does not deposit soot, and if

FIG.

7.

FIG.

8.

a Bunsen burner cannot be used, an alcohol lamp, Fig. circular wick 10 to 15 mm. in diameter, is needed. Such a lamp, however, is not adapted
for use with the blowpipe, as the flame
is

9,

with a

not

rich

enough

in carbon to

give suitable re-

duction

effects.

Platinum-pointed Forceps.

These are

in-

dispensable for holding fragments of minerals

which are to be heated before the blowpipe. Fig. 10 represents the usual form. They are FlG 9 made of steel, and should be nickel-plated. The platinum points are opened by pressure, and are rendered self-closing by means of a spring, which should not be too strong. The platinum needs occasional cleaning, which is best done by scouring with sea-sand.

FIG. 10.

The

steel

ends are useful for picking up and handling fragments

of minerals

and

for detaching pieces

from specimens.

The only

precaution that is needed in the use of the forceps is never to allow minerals with metallic luster to fuse against the red-hot platinum, since the latter may form a fusible alloy with lead, arsenic,

16

APPARATUS.

antimony, or other readily reducible elements. If the platinum does become alloyed, it is best to cut off the ends of the forceps,

and reshape them with a file. Platinum Wire. This is used for supporting beads of fused borax, salt of phosphorus, or other fluxes, and for introducing powders into the flame. A kind about 0.4 mm. in diameter
(weighing 0.247 grs. for every 10 cm.) is best. Loops. For the support of fluxes, loops, Fig. 11, are used, which are made by bending the platinum wire over a
4
conical point. As a rule, these loops should be from 3 to mm. in diameter. The beads may generally be removed

by straightening out the wire, or sometimes by dissolving them in acid. The double loop is made by grasping the wire in the
end of the platinum-pointed forceps, and making a double turn about the latter. It is only recommended to serve as
s t e el
FIG. 11.

to be fused with

an additional support when a considerable quantity of material some flux. _^

Holders.

is

contrivance

like

mmmit

Fig. 12 is convenient for holding platinum wire. Short pieces of wire

may

also be fused into the

end of a glass tube or rod. Platinum Spoons. These may be usefully employed in a few operations where fusions are to be made. Preferably the spoon, Fig. 13, should have a bowl 18 to 20 mm. in diameter, and need not weigh over 1.25 grams. It
held in tne platinum forceps, and the fusions maybe soaked out by digestion in a test-tube
is
FIG. 13.

with water or acids.

dles, Fig. 14,

Spoons with long hanare often recommended, but

FlG 14
-

they are necessarily heavier, and are not very serviceable bowls are small.
Charcoal.

if

the

This is used in many operations as a support for the assay, and, moreover, the carbon often assists in bringing about reductions. For most purposes, any piece of well-burned

APPARATUS.

17

charcoal that does not snap nor become fissured in the flame will
suffice.

recommended.

The kinds made from basswood, pine, or willow are It is a good plan to have the material sawed out
blocks
of

into rectangular

about 10

cm.

Excellent

charcoal, prepared especially for blowpipe work, can be procured

from

dealers.
is

Usually the assay

best heated on a smooth, flat surface,

although occasionally a slight depression or cavity, which cut with a penknife, is needed.

may

be

good piece of charcoal

will last for

some time, a clean

sur-

face being afforded been used.

by

filing or cutting

away the part

that has

For the uses of charcoal,

Tablets.

see p. 39.

These are prepared by making plaster of Gypsum Paris into a thin paste with water, pouring this upon a sheet of
glass,

and spreading

it

out evenly until

it is

about 3 or 4
off

mm.

Before the plaster sets, its surface a knife into rectangular blocks about
thick.

is

4x8

by means of cm. across, which are

ruled

removed
These

after the plaster hardens.

tablets are admirably adapted for collecting sublimates, especially recommended by Haanel,* are used as follows:

colored ones, and, as

tablet,

finely powdered material to be tested is placed near one end of the moistened with a few drops of hydriodic acid, and heated at the tip The iodides, as they volatilize, condense on of a small oxidizing flame. White as coatings, some of which are very beautiful. the white gypsum be collected on tablets which have been previously blackened coatings may

The

by holding them over a sooty flame. As a substitute for hydriodic acid, Wheeler and Luedekingf have found that ordinary tincture of iodine answers in most cases, and an iodide of sulphur, prepared by fusing 4 parts by weight of iodine and 6 of sulphur, is of still more general application. Moses J suggests using a flux prepared by mixing 2 parts of sulphur, 1 of potassium iodide, and 1 of potassium bisulphate.

Glass Tubing.
3 to 6

mm.

supply of hard glass tubing, varying from in internal diameter, is needed for making closed and
Canada, Section
III, p. 65, 1883.

open tubes.
* Trans. Roy. Soc.
t Trans. St.
1

Louis Acad. of

Sci., vol. iv, p.

676, 1886.

School of Mines Quarterly,

New

York,

vol. x, p. 320, 1889.

18

APPARATUS.

Closed Tubes.

These are tubes closed at one end, Fig. 15, and should be about 8 cm.
long,

and 3

to 4

FlG
ily

15>

nal diameter.

mm. in interThey may read-

be made by heating a tube of twice the required length, at the middle, in a Bunsen-burner flame, and turning it slowly so that
the glass will be uniformly heated. When the glass becomes quite soft, the tube is removed from the flame and pulled in two.

The slender terminations are then removed by holding the end of the tube nearly through the flame, allowing the glass, where it has been pulled out and is quite thin, to fuse together, and then pulling

away the

termination.

These tubes are used for heating substances out of contact Substances are best introwith, or with but limited access of, air.

duced in the form of fragments, which drop to the bottom of the

tube, leaving the walls perfectly clean.

be observed, when substances are heated in closed tubes, are the distillation or giving off of volatile products (gases, liquids, or solids), which collect in the upper, cold part of the tube but any change which the material

The principal

effects that

may

undergoes should be carefully noted. For a list of the closed- tube reactions, see Chapter IV, p. 139. Bulb Tubes. Tubes with a bulb at one end, Fig. 16, are

employed in a number of operations. They may be made by heating the end of a tube like that shown
in Fig. 15 over a blast-lamp until the glass becomes quite soft,

and then blowing a bulb of the desired size. With a Bunsenburner or alcohol flame, sufficient heat cannot be obtained to make these tubes from hard glass, but if one is not able to blow them, they can be procured from dealers. A good size for the bulb is from 12 to 18 mm. in diameter.

Open Tubes.
employed

These are tubes, open at both ends, which are in heating or roasting substances in a current of air,

APPARATUS.

19

and thus bringing about oxidation. The tubes should be from 5 to 7 mm. in internal diameter and 15 to 17 cm. long. The substance (best in the form
of
fine

powder, so as to expose a surface to the air) is placed about 4 cm. from one end.

maximum
may

This

be readily accomplished

of paper, folded into a

by putting the powder upon a slip Y-shaped trough,

slipping this to the desired distance into the tube, and inverting. The tube, held in a slanting position (from 20 to 30), with the powder in the lower end, is

heated for some time, first just above the substance to insure a draft of air, and finally directly

FIG. 17.

then

Straight tubes can be used for almost all experiments, but sometimes the powder has a tendency to fall out, and then

under

it.

a bent tube, Fig. 17, may be used. The powder is placed near the bend, and the flame applied somewhat above it so as to insure a
draft of
air.

For a

list

of the open-tube reactions, see Chapter IV, p. 141.

Diamond Mortar. The most convenient form is shown in It is made from the very best tool-steel, and is almost Fig. 18.

FIG.

18.

FIG. 19.

small fragment, not indispensable for pulverizing minerals. over 5 mm. in diameter, is placed in the cavity; the pestle is then

APPARATUS.
inserted,
pestle,

and struck several sharp blows with a hammer. which should not fit too closely, is twisted so as

If the

to give

a sort of milling motion, a very fine powder can be obtained. The mortar can be readily cleaned by grinding up bits of glass

and wiping the cavity and pestle with a dry

Mortars made in three parts, Fig.
19,

cloth.

which are frequently

recommended and kept

in stock

by

dealers, are not as serviceable

as the kind described in the foregoing paragraph. Agate Mortar and Pestle. These, Fig. 20, are used for reduc-

ing minerals to a very fine powder. The mortar should be from 5 to 8 cm. in diameter. The

mortar and pestle are used for grinding, never for pounding hard bodies.
If a diamond or agate mortar is not at hand, be pulverized by wrapping in several folds of thick may A cheap porcelain mortar will also paper, and hammering on an anvil. serve for grinding all but very hard minerals.

mineral fragments

Hammer.
poses.
Anvil.

small, artisan's

hammer

will

answer most pur-

A small block of

hardened

steel,

or

any convenient
is suitable.

flat

steel surface (as the Pliers.

base of a diamond mortar)

Cutting-pliers are very serviceable for detaching

and

breaking up small fragments of minerals.

Those

shaped like Fig. 21 are made especially for this purpose, but ordinary pliers, such as are used for
cutting wire, are an excellent substitute. File. small three-cornered file is used for

notch is cut in one side of cutting glass tubes. the tube, which is then half pulled, half broken in two.

Magnet.

A common

horseshoe magnet, or a
FIG. 21.

magnetized knife-blade, serves to recognize magnetic bodies. magnetic needle is sometimes

useful for delicate determinations.

Lens.

good magnifying-glass

will be

found very useful.

APPARATUS.

21

An

achromatic

triplet, of

about

1 inch focal length, is best,

but

is

expensive, and a cheaper form of lens will answer. number of these, from 3 to 4 cm. in diamWatch-glasses.

eter, will

be found convenient for holding mineral fragments and Small butter-plates or white powders. porcelain India-ink slabs with three or

more depressions serve the same purpose.

Metal Scoop.
This,
Fig.
22,
is

well

FIG.

22.

adapted for handling powders,

and especially for transferring

them

to tubes.

Ivory Spoon and Spatula. An ivory spoon, Fig. 23, with a bowl 5 X 10 mm. inner diameter, is useful for handling powders

FIG. 28.

The handle, if and dry reagents. thin and flat, serves as a spatula for handling and mixing reagents.

A knife-blade also makes an

Test-tubes.

excellent spatula. For making tests in the wet way, test-tubes are

very necessary. from 15 to 20

They should be

mm.

in diameter

A large and about 16 cm. long. feather will be found very convenient for cleaning such tubes.

test-tube stand, Fig. 24,

and some
use

form

of

holder,

for

when

FIG- 24. liquids are to be boiled, should be obtained. One like Fig. 25 can be cut from a piece of pine.

FIG. 25.

Beakers and Flasks.

prove of much service. of over 150 cc.

few of these, of various sizes, will The largest ones need not have a capacity

Funnel and Filter-paper.

glass funnel about

cm.

in

APPARATUS.

diameter and a supply of filter-papers are needed. It will be well to buy cut papers, 7 and 9 cm. in diameter, from dealers.
Filtering and Washing. paper is folded twice upon
this is

To make a

filtration,

a piece

of

itself, thus forming a quadrant, and form a conical cup, having three thickopened nesses of paper on one side and one on the other. It is snugly inserted into a dry funnel, and moistened with water. The

so as to

material to be filtered

taken not to have

run

out,

water

is

then poured upon the paper, care being above the top. When the liquid has all go added till even with the top of the paper, or
is
it

dropped around the edge so as to moisten every

repeating this several times,

part.

By

the soluble materials are wholly washed away from the insoluble
portions.

Porcelain

Dishes.

Those with

handles, called casseroles, Fig. 26,

FIG. 26.

most convenient for boiling liquids and making evaporations.

are

From

7 to 9 cm. in diameter is a

good

size.

Porcelain Crucibles.

These should be about 3 cm. .in diameter,

and are useful in a number of ways, especially for obtaining a small quantity of a precipitate which has been collected upon a

FIG. 27.

FIG. 28.

filter-paper

and needs

to be subsequently examined.

For

this

purpose the paper is put into the crucible, and the latter, supported on a triangle made of iron wire, Fig. 27, is heated over a

APPARATUS.

23

until the carbon of the paper has completely burned away, leaving the precipitate together with the trifling ash of the paper.

lamp

Lamp-stand.
like Fig. 27
coil of

This

may

be

be purchased from dealers, or one easily made. By slightly bending the

may

wire which goes about the upright, the proper degree of tension may be obtained, so that the ring will move readily

up and down, and yet stay

Wash-bottle.

fixed in
28,

any

position.
flask, or

This, Fig.

can be made from a

from any bottle having a neck wide enough to receive a doubly

perforated stopper.

Dropping-bottles and bulbs. A form like that shown in Fig. 29, about 35 mm. in diameter, is convenient for water, when only a small quantity is

two thirds full, by closing the larger opening and inverting, the heat of the hand will expand the air and
needed.
If less

than

drive out the water drop by drop. represents a form with a bulb 30
diameter, and
is

Fig. 30

mm.

in

FIG. 29.

convenient for holding reagents which In order to fill it, a drop at a time, are to be used

the

bulb

is

warmed and the end dipped under the

This
is

surface of the liquid, when, on cooling, a few

drops of the latter will enter.

boiled to expel

then

the

air,

and the

tip again

FIG. 30. brought quickly under the liquid, when the condensation of the steam will cause the liquid almost immediately to rush in. The bulb should not be more

than two thirds

full.

convenient form of dropping-

FIG. 31.

bottle with hollow stopper is

shown

in Fig. 31.

Pipette.

glass tube of 5

mm.

inner diameter, heated over

a lamp and drawn out to a capilwill serve as a lary, Fig. 32,

FlG 33
-

pipette,

for taking

up small

quantities of

and will be found useful liquids and introducing them

into tubes,

24

REAGENTS.

PART

2.

REAGENTS.

Reagents are substances employed to produce changes in

bodies, in order to test their composition. They are known as dry, gaseous, or wet, according as they are used in the solid, gaseous, or liquid form. Most of them can be obtained, suffi-

The ciently pure, at drug stores or from dealers in chemicals. solids and liquids should be carefully labelled and kept in suitable,
For greater convenience, however, it is well-stoppered bottles. well to have on hand a supply of some of the more common dry reagents in wooden or glass pill-boxes about 4 cm. in diameter.

DRY REAGENTS.
Sodium Carbonate, Na,CO
s
.

Dry sodium carbonate may be

purchased, or it may be made by heating the commercial bicarbonate in a porcelain dish until it becomes anhydrous. Sodium
is used for decomposing many substances, and owes its action to the tendency of sodium to unite with non-metallic or ZnO CO2 ISTa^O, Na,S acid-forming elements. Thus, ZnS

carbonate

Fusions with sodium carbonate are frequently made in a loop on platinum wire, and in order to obtain a bead, it is recommended
to

make

up

the material into a thick paste with water, to take this The in the loop, Fig. 11, and to fuse in an oxidizing flame.

bead should be clear when hot, but white and opaque when cold. If heated in the reducing flame, it will be brown, owing to the
presence of carbon. For a list of some of the reactions with sodium carbonate, see

Chapter IV, pp. 145 and

151.
4 7

.10H 2 O. The crysBorax, or Sodium Tetraborate, JNa a B tallized commercial salt is usually sufficiently pure, and is broken
into coarse

powder for use. Borax is generally fused into a bead on platinum wire, and to make this, the platinum loop, Fig. 11, is heated and touched to the salt, and the adhering material fused before the blowpipe until a clear glass is obtained. The bead To should be lenticular in shape, and clear and colorless.

REAGENTS.

25

introduce the material to be tested into the bead, touch the latter when hot to a small particle of the substance, or to a little of the

powder, and heat before the blowpipe.

Borax

dissolves various

substances, especially the oxides of the metals, them gives characteristic colors.

and with many of

Chapter IY, p, 148. Borax-glass. This is needed for only a few experiments. A little at a time may be made by fusing borax in a rather large loop on platinum wire, and crushing the glass in a diamond
list of

For a

the

tests, see

mortar.

It

may
4

also be purchased.
Salt,
4

Phosphorous
phate,

or
2
;

Hydrogen Sodium Ammonium Phossometimes called Microcosmic Salt

HNaNH PO .4H

This

is

made

in the

generally fused into a bead on platinum wire. The bead is same way as the borax one, but the material becomes

very liquid, and is apt to drop from the loop when first heated. This may be avoided, however, by heating gently at first, and
holding the bead just above the flame, so that the escaping steam and the force of the blast may buoy up the liquid. The salt is

The changed by fusion to SODIUM METAPHOSPHATE, NaPO sodium metaphosphate beads are mostly similar to reactions with those with borax, and a tabulated list of them will be found
3
.

in Chapter IV, p. 149.

Blue litmus- and yellow turmeric-paper may be purchased from the dealers. The former is turned red by acids, and the latter reddish-brown by alkalies. The turmeric-paper also serves for the recognition of boracic acid and zirconium. For use, these papers are conveniently cut into narrow strips.
Test-papers.

K S 0,
2

Potassium Bisulphate, HKSO and Potassium Pyrosulphate sometimes called Acid Sulphate of Potash. This can be 2
4
,

made by heating

crystallized potassium sulphate with half its

weight of concentrated sulphuric acid (10

grams

K SO
2

and 3

cc.

in a porcelain dish until vigorous frothing ceases. The 2 SO ) fusion solidifies to an opaque mass, which should be pulverized
4

and preserved in a well-stoppered HKSO into pyrosulphate, K S O,, and

4
2

bottle.

finally to

Heating changes normal sulphate,

26

REAGENTS.
4
.

variety of minerals are decomposed by fusion with potassium bisulphate, and such fusions may be made either in the platinum spoon, porcelain crucible, or often even in a test3

K S0

tube.

Potassium Bisulphate and Fluorite.

materials,

mixed

finely pulverized in the proportion of 3 parts of the former to 1 of

The

the latter, are useful for detecting boron in some of its combinations, and it is well to have a small supply of the mixture on

hand.

The mixture when heated

liberates

hydrofluoric

acid.

2HF. CaSO 4 CaF, = K,SO 4 Potassium Iodide and Sulphur. The pulverized materials, mixed in equal proportions, are used for detecting bismuth and

2HKS0

lead.

Oxide of Copper, CuO.

A little

of the oxide

may

useful for detecting chlorine. be purchased, or made by dissolving

is

This

copper in nitric acid, evaporating the solution to dryness,

igniting to redness in a porcelain dish.

and

A little powdered cuprite

is

or malachite will answer equally well. Potassium Nitrate, This

KNO

used

occasionally

for

fusing with minerals when an oxidation is required. Bone-ash, This is needed for the silver assay. It will be best
to purchase a small supply from a dealer.

be purchased from the dealers. The first two are used, generally with acids, in making reductions, as they dissolve in acids with evolution of

Granulated Tin, Zinc, and Lead.

These

may

hydrogen, and change many combinations from a higher to a Zn = 2FeCl 2 lower valence. Thus, 2FeCl 3 ZnCl 2 or possibly H = FeCl, HC1. Lead is used for the silver assay, Fed,

and should be
lead.

free

from

silver.

This

is

commonly

called test-

Magnesium.
acid.

This

may

be useful for detecting phosphoric

It is best to

have the magnesium ribbon.

EEAGENTS.

27

GASEOUS EEAGENTS.

Hydrogen Sulphide,
needed
ratus
it

H S. When
2

little

of this reagent is

may

be generated in the simple appa-

shown in Fig. 33. The bottle contains fragments of ferrous sulphide, FeS, and concentrated hydrochloric acid diluted with an equal volume
of water is poured in through the thistle-tube, so as to give as nearly constant a flow of gas as pos-

By means and a rubber connection, the gas may be led into any liquid in order to bring about
sible.
2

FeS

+ 2HC1 = H S + Fed,.

of a glass tube

a precipitation.
Chlorine, Cl.

but a

little

This reagent is seldom needed, of it may be prepared by warming

powdered pyrolusite,
hydrochloric acid
chlorine

MnO

with concentrated
off

(p. 101),

and carrying

the

FIG. 33.

by means

forated cork.
gas, is

of a bent glass tube running through a perCJilorine-water, or water saturated with chlorine

sometimes used.

WET REAGENTS.

Wet

reagents, especially acids, should be kept in bottles with

ground-glass stoppers, and should be handled carefully. Acids when boiled give off disagreeable and corrosive fumes, and it is quite essential that these should be carried off by a good draft,

which may be accomplished by arranging a hood or small chamber

connecting with a chimney-flue. If acids are spilled upon fabrics, the spots should be immediately moistened with ammonia to
neutralize the acid,

and then thoroughly washed with water.

Water.
substituted.

Distilled water is best, but clean rain-water

It is

may be

convenient to keep a supply of water in a wash-

bottle, Fig. 28.

Hydrochloric Acid,
gas in water.

HCL

This reagent

is

a solution of

HCi

The pure concentrated acid

of the dealers contains

28

REAGENTS.
it is

about 40^ HC1, and for most operations diluted with an equal volume of water.
Nitric Acid,

best to use the acid

useful for dissolving many minerals, and in the concentrated form it is a strong oxidizing agent. The acid is exceedingly corrosive and needs to be handled very
S.

HNO

This

is

carefully,

Nitrohydrochloric Acid, or Aqua Regia. This mixing 1 part of nitric acid and 3 of hydrochloric. ful solvent and oxidizing agent.

is

It is

prepared by a power-

Sulphuric Acid,

H SO
2

or Oil of Vitriol

This needs to be

handled with
heat
is

much

care.

When
it.

added

to water, a great deal of

C.),

generated, and

when hot

(boiling-point 338

water

For many tests it is well to employ a dilute acid, made by adding 1 volume of acid to 4 of water. Hydriodic Acid, HI. This is needed for only a few tests, and
should never be added to
does not keep well, as it decomposes, with separation of free It may be prepared by suspending iodine in water, passiodine.
ing hydrogen sulphide gas into the liquid until the solution becomes colorless, and then decanting from the separated sulphur. It is convenient to keep a supply of this in a dropping-bottle,
Pig. 31.

Hydrochlorplatinic Acid, often called Platinic Chlo2 PtCl 6 ride. This is useful for detecting potassium in presence of lithium and sodium. Its preparation is explained under platinum (Chapter III, p. 103).
;

Hydroxide, OH; commonly called Ammonia. a solution of ammonia-gas, in water. It is a strong alkali, and should not be added to acids unless the latter
4

Ammonium

NH

This reagent

is

NH

3 ,

are cold and dilute.

another strong alkali. does not keep well in glass, and it will be found more convenient to have the stick potash broken up and preserved in a
is

Potassium Hydroxide,

KOH.

This

Its solution

well-stoppered bottle.

Barium Hydroxide, BaO H A solution of this may be prepared by dissolving the crystallized salt in 20 parts of warm water,
2 2
.

REAGENTS.

29

cooling and filtering off the insoluble material, which consists Calcium hydroxide, lime-water, mostly of barium carbonate.

be substituted, and is prepared by shaking up a small quantity of quicklime with water, allowing this to stand for some hours, and then decanting off the clear liquid.

CaO,H

3 ,

may

Ammonium
saturating a

Sulphide,

(NH

4)2

S.

This

may

little

ammonia with hydrogen

be prepared by sulphide, and then

On long adding two thirds the volume of the same ammonia. it turns yellow, and then contains an excess of sulphur. standing Ammonium Molybdate, (NH ) Mo0 This is almost indis4

4.

pensable for the detection of phosphates.

It

may

be prepared by

ammonia, and pouring the dissolving molybdic oxide, solution into dilute nitric acid, being careful to have an excess of The solution is allowed to stand, and anything that the latter.
3
,

MoO

in

may

separate out

is filtered off.

Cobalt Nitrate,

Co(NO

3) 2

The

crystallized salt is

dissolved

in 10 parts of water, and the solution kept most conveniently in a It is used for moistening infusible dropping-bulb, Fig. 30.

substances, especially those containing aluminium and zinc, which are afterwards intensely ignited before the blowpipe, and assume
characteristic colors.

Cobalt nitrate

when

ignited

is

decomposed,
3

yielding a deposit of cobalt oxide upon the assay, (Co(NO ) 2 OoO 2NO 2 O), and this oxide unites with it, giving colored

compounds

of

unknown composition.

The reagent may be applied

to a fragment of mineral held in the platinum forceps, but the reaction usually succeeds better if the finely powdered mineral is

made
of

into a thin paste with the cobalt nitrate solution,

is

and a

little

placed upon charcoal, recommended for hard blowpipe. This latter method is especially
this,

intensely ignited before the

and compact minerals.

Aqueous

solutions of the following salts

or, if

may

be kept in glass-

they are to be used only occasionally, it is recommended to keep a supply of the pulverized dry salts on hand, and to dissolve a small quantity in a test-tube when needed.
stoppered bottles,

Ammonium

Carbonate,

(NH ) CO
4

3.

The commercial, dry

salt

30
is

REAGENTS.

a mixture of

ammonium
.

bicarbonate,

HNH C0
4

3 ,

2 carbamate, 3 regarded as containing normal

NH NH CO

Its solution in water, however,

and ammonium may be

4 2
3
.

Ammonium
called

ammonium carbonate, (NH ) CO .2H O. Oxalate, (NH ) C Di-Sodium Hydrogen Phosphate, Na HP0 .12H O commonly
4

Sodium Phosphate.
2

Barium Chloride, BaCl .2H O.

8

Silver Nitrate,

AgNO

Potassium Ferrocyanide, Potassium Ferricyanide,

K Fe(CN) .3H O. K Fe (CN) An

4

ja

aqueous solution

of this salt does not keep well.

Ammonium
The
list

Sulphocyanate,

NH CNS.
4

wet and dry, might be considerably but the principal ones have been given, and those not in enlarged, the list which are mentioned in subsequent chapters can be easily
procured.
ratory

of reagents, both

Any

may

reagents used in a well-equipped chemical laboat times be found convenient.

Of the foregoing reagents, water and the acids are commonly employed for dissolving substances. The appropriate solvent for a mineral can be learned only by experience or by a knowledge of the chemical composition of the material. As most
Solution.

minerals are insoluble in water, its use as a solvent is limited. Hydrochloric acid is most generally employed, and is preferred to other strong acids, as it is safer to handle. Nitric acid is needed

when an oxidation
to be dissolved.

is

required, as

when sulphides

or arsenides are

seldom necessary to use sulphuric acid. In order to dissolve a mineral it is best to treat some of the very finely powdered material in a test-tube with from 5 to 10 cc.
It is

of the solvent (it may be necessary to try several solvents before the appropriate one is found), and, if the material does not dissolve in the cold liquid, the contents of the tube should be hea/fced to boiling, which, in the majority of cases, greatly facilitates solution.

Precipitation.

When

insoluble

compounds are formed by

adding reagents to solutions, the process is called precipitation.

NATURE OF FLAMES.

31

When

solutions are mixed, precipitation will take place, provided

an insoluble compound can be formed by the interchange of the chemical constituents. For example, when aqueous solutions of sodium chloride and silver nitrate are mixed, a white precipitate
of silver chloride will be formed, because silver chloride
T JN aCl

is insol-

uble in water. NaNO s AgCl Precipitation furnishes a means for detecting many elements, and it is also useful for separating substances, since the insoluble precipitates
.

+ AgNO, =

maybe

collected

on

filter-papers

and thus removed from

solutions.

PART

3.

ON THE NATURE AND USES

OF FLAMES.

Combustion. This is ordinarily an oxidation process, and where a flame is produced, the latter results from the combination of carbon and hydrogen of different gases and vapors with the

oxygen
dioxide,

of the air, the final products of the oxidation being carbon

2
,

CO and When a lamp

and
is

water,
-or

H O.
2

candle
is

is

burning,

the

oil

or the melted

material of the candle

attraction,

carried

there converted

up by the heat
chemical

into the

wick by capillary
of the flame into

gas or vapor,

which burns.
are

Such
definite

gases, as w^ell as ordinary

compounds, but mixtures, usually of different combinations of carbon and hydrogen, and are known as hydrocarbons. Water-gas, with which
illuminating-gas,

not

many

cities are

glowing coals, 2H CO. The resulting gas (a mixture of hydrogen and carbon monoxide), which burns with a non-luminous flame, has to be mixed with some volatile material rich in carbon, in order to
:

now supplied, is made by blowing steam through when the following reaction takes place H O +C =
2

make it luminous, The Candle Flame.

senting

This, Fig. 34, has been chosen as repre-

typical luminous flame,

and may be regarded as

:

containing three distinct parts, as follows the gases are fully exposed (1) An outer part, a, where to the oxygen of the air, and where the combustion is com-

32

NATURE OF FLAMES.
;

plete

that

where carbon is burned to CO and hydrogen to H 2 O. These gases form an invisible envelope about all
is,
2
,

luminous part of the an incomplete combustion, flame, is characterized by since only a limited supply of oxygen, which penezone,
,

ordinary flames. (2) An inner

the

trates the outer envelope, is available.

burns to

Hence, carbon lower oxide, carbon monoxide, CO, while 2 0. Moreover, the heat of the flame hydrogen forms some of the gas, with separation of finely decomposes
its

divided carbon.
FIG. 34.

This being heated to incandescence

renders the flame luminous, and will deposit as soot

upon any cold substance held in the flame. within the flame is the zone (3) Still further
the unburned
gases as they are first formed

c,

which contains

by the heat and rise up from the wick. The three zones, a, 5, and c, naturally grade into one another, and are not separated
by sharply defined boundaries.

A
:

G-\

The Bunsen-burner Flame.

This, Fig. 35,

has three zones corresponding to a, b, and sufficient c, of the candle flame, except that
air
is

allowed

to

mix with the gas

to

prevent the separation of carbon in b. The flame, therefore, is non-luminous and deposits

no

soot.
2

The outer envelope,

2

a, contain,

ing

C0 and H
;

O, is invisible; the zone

2
,

and H O, is pale containing CO, some CO and the inner zone, c, containing a violet mixture of unburned gas and air, is sharply
2

outlined against b

by a pale blue

border.

Special precautions should be taken that the flame does not snap down and burn at

FIG. 35.

the base.

USES OF FLAMES.

33

produced by placing the tip of the blowpipe into the gas or lamp flame, and blowing a moderately strong blast of air. If a gas flame is used, it should burn
is

The Blowpipe Flame.

This

from the

jet

e,

Fig.

4,

p. 13,

and should be from 3

high.

to 4 cm.
p

The operator should be comfortably seated at the table, his arm resting upon its edge, and the blowpipe grasped near

FlG

36>

the water-chamber, between the thumb and first and second The blast should be so regulated fingers of the right hand.
that the flame will be deflected into a slightly tapering, distinctly outlined, blue cone, Fig. 36, in which the zones a, &,
.

and c, correspond exactly to those of the Bunsen-burner flame. The flame should not appear luminous, except, perhaps, a small portion just above the blowpipe tip, which is not carried along

by the

draft.

If the hole in the tip is well bored, the flame will

neither flutter nor

strongest.

show

irregularities,

even when the blast

is

Heating and Fusion.

is at r,

Fig. 36, just point, minerals are heated to determine their fusibility or other

The hottest part of the blowpipe flame beyond the tip of the inner blue cone. At this
exhibit.

phenomena which they may

melted
if

Even platinum can be readily

in the form of fine wire (not over 0.2

mm.

in diameter),

so as not to radiate nor conduct

too rapidly. In testing minerals, the size and shape of the fragment to be used is a matter of considerable importance. If too large, it is

away the heat

often impossible, to heat it up to the desired temperature, while, if too small, the reaction may not show with sufficient distinctness. Beginners almost invariably err in taking too large
difficult,

pieces.

Usually the reaction succeeds best either with a splinter or a fragment with a thin edge, and a size about as large as a leadpencil point (1 mm. in diameter and 4 mm. long) can be recom-

mended.

The fragment should be held

in the forceps in such a

34

USES OF FLAMES.
of
it

manner that the greater part

num
not

projects free beyord the plati tips in order that heat may

be

wasted in warming

up

the metal, and so that a point or thin edge of the mineral is turned in the

Any change which the mineral undergoes may be a help in its identification, and should be carePIG. 37. fully noted e.g., whether fusible or infuthe degree of fusibility and the sible, and in the former case manner in which the mineral fuses, whether quietly or with intumescence (swelling); whether to a clear, white, or vesicular a light- or dark-colored mass (full of bubbles) glass; whether to
;

direction of the flame, Fig. 37.

or slag, or to a magnetic or non-magnetic mass. Decrepitation. It frequently happens that a mineral, when introduced into the blowpipe flame, snaps or explodes, so that it
is difficult

and often impossible to secure a piece which can be held in the forceps and heated. This phenomenon, known as decrepitation, may be due to unequal expansion of the material. More often, however, it results from the presence in the mineral of minute cavities containing gases or liquids (commonly water, sometimes liquid carbon dioxide), the expansion of which causes
the explosion.

At times
forceps, if at flame, so that

a fragment of a decrepitating mineral may be heated in the first very carefully introduced into the ordinary gas or lamp it becomes slowly and uniformly heated before being subjected
of the blowpipe flame.

to the

more intense heat

Another way

is

to heat sev-

eral large pieces in a closed tube until decrepitation ceases, when, on dumping out the fragments, one may be selected of the right size and shape to be

taken in the forceps and heated before the blowpipe. When the above methods fail, the following, suggested by Berzelius, may be resorted to: Grind the mineral to a very fine powder, make into a thin paste with water, then spread out a drop of this upon a clean charcoal surface, and heat
before the blowpipe, at first very gently, finally as intensely as possible. If fusion has not already been observed, a coherent cake will usually be
obtained, which with care can be lifted in the forceps, and duced into the blowpipe flame.
its

edge intro-

USES OF FLAMES.

35

Flame

Coloration.

The heat

of the

blowpipe flame

is

so

intense that

many substances are volatilized, and several of the elements in them may then be recognized by the colors they impart to
the flame (compare table, Chapter IV, p. 136). The test may be made with a fragment held in the clean platinum forceps, as shown
in Fig. 37, but usually it succeeds better when a minute quantity of the finely powdered material is taken upon a clean platinum

wire and introduced into the Bunsen-burner or blowpipe flame. For the latter purpose, a wire may be cleaned by heating until it

imparts no coloration to the flame, or, if there is much material adhering to it, it may be boiled in any strong acid, then washed with water and heated (compare Sodium, p.115, 1,6). The straight

next moistened with pure water, and its end touched to the powdered mineral so as to take up a minute quantity of the
wire
is

material,

which

is

then introduced into the flame.

Often the

merest trace that will adhere to a dry wire is sufficient to give a The tests are, as a rule, exceedingly magnificent flame color. and the essential condition to be fulfilled is that the delicate,
material shall be heated
liot

enough to

volatilize the

element or

Often a sufficient temperature cannot be obtained when a rather large fragment held in the
color.

compound which gives the

or considerable

forceps,

material

supported in a loop on plati-

num

wire, is heated before the blowpipe.

dark room, but as this is usually not convenient a dark screen (book-cover) as a background will be
colors are best seen in a

The

found advantageous.
Oxidation.

By

oxidation

is

meant the union

of a substance

with oxygen (compare Combustion, p. 31). Many substances when heated before the blowpipe readily take on oxygen from the

The flame then imparts nothing to them, about conditions favorable for the taking up of but simply brings oxygen. For example, pieces of wood or a copper wire under
air

and are oxidized.

ordinary conditions
are

be kept almost indefinitely, but if they intensely heated, with access of air, the former burns, or

may

36

USES OF FLAMES.

oxidizes,

and the

latter is gradually converted into

copper oxide,

CuO.
Oxidizing Flame. The flame represented in Fig. 36 is usually called the oxidizing flame, and the part favorable for oxidation is at o, beyond the blue and violet cones, c and 5, and especially

where the

air

can and the carbon monoxide in b cannot have

access to the substance.

Usually by the term reduction is meant the taking away of oxygen. In a more general sense, it may refer to the formation of a metal from any of its compounds, or to the
Reduction.

change of some element in chemical combination from a higher to a lower valence. Thus, the conversion of CuO or Cu 2 S to metallic copper, or of FeCl 3 to FeCl 2 (ferric to ferrous chloride), would be

spoken of as reductions. Reducing Flame. By means of the blowpipe flame, reductions are made by taking away oxygen, and this is accomplished by
heating substances so that they are exposed to the action of carbon monoxide. Carbon monoxide, CO, is a reducing gas, since it

has a tendency to take on oxygen and become carbon dioxide,

FIG. 38.

CO

give up their oxygen, and are reduced either to a metal or to a lower oxide. The
3.

Many

oxides, therefore,

when heated with CO

following equations will illustrate this:

CuO + CO = Cu-fCO and

2
,

Fe

+ CO = 2FeO + CO
r,

2.

for reduction is at

Fig.

The part of the flame most favorable 36, where the heat is intense and carbon

monoxide predominates.
quently impossible to
like that

When

a substance

is

large, it is fre-

make a satisfactory reduction in a flame in Fig. 36, for, while a portion is exposed to the action of carbon monoxide in the zone 5, another portion must
shown

USES OF FLAMES.

37

project into the air and will there have a tendency to oxidize. In such cases, a broader flame, Fig. 38, should be used. This is made by deflecting the gas or lamp flame by a gentle blast, and

regulating the latter so that the flame is slightly luminous, but still does not deposit soot upon the assay held at r. Reductions are frequently made on charcoal, and the reducing
action of the carbon

monoxide

is

then augmented by that of the

glowing carbon.

The following experiments

application of the blowpipe
:

will serve to illustrate the use

and

a. To prove that water, H 2 0, arid carbon dioxide, C0 2 , are products of combustion, take a dry bottle and for a few seconds deflect a small blowpipe flame down into it, Fig. 39. The water which condenses on the sides of the glass has

resulted from the oxidation of the hydrogen in the gas. That the bottle also contains C0 2 may be

proved by adding a

little clear

barium hydroxide

water, inserting the stopper, and shaking, when a white precipitate forms, which is barium carC0 3 +Ba0 2 2 BaC0 3 -hH 2 0. bonate, BaC0 3
.

H=

the intense heat of the blowpipe FlG flame, and to acquire skill in the manipulation of the instrument and in maintaining a continuous blast, fuse platinum wire and fragments of minerals used in the scale of fusibility (p. 230). The
b.
-

To show

it

platinum wire should not be over 0.2 mm. in diameter, and it is best to bend near the end and hold it end on toward the flame (compare Fig. 37).
c.

unburned

To show that the inner portion of a flame contains a zone of gas, make use of a Bunsen-burner flame, Fig, 35, and hold a glass

it at r until it becomes quite soft; then remove from the flame, and draw out to a narrow tube. Next, hold the narrow tube across the flame at s, and observe that it softens in two places where it passes through

tube across

the edges of the flame, but the portion within the cone c neither fuses nor becomes red-hot. By holding one end of a rather narrow glass tube in c, a little of the unburned gas may be drawn off to one side, and burned at the
other end of the tube.
(L

To make
is

a flame test, take a fragment of barite,

as

BaS0

4 ,

in

the

forceps, and heat before the blowpipe,

color

obtained.

Barium imparts a

in Fig. 37, until a distinct yellowish-green coloration to the

shown

outer part of the flame.

ity,

Barite also fuses at about 3 in the scale of fusibil-

and

Is

very apt to decrepitate.

Also test the flame coloration by taking

38

USES OF FLAMES.

barite on platinum wire, as directed on p. 35, and heating both in the blowpipe and the Bunsen-bnrner flames. In the latter case, introduce the material into the edge of the flame, at about r, Fig. 35.

up powdered

reducing character of the blowpipe flame, make some with hematite, Fe a 3 (a splintery variety is best), which should experiments not be magnetic before heating, but becomes so upon reduction to a lower oxide, FeO. Taking a fresh fragment for each experiment, hold it in the
e.

To

test the

forceps, and heat before the blowpipe for several seconds at the points

o, r,

and s, Fig. 36, and, after cooling, test with a magnet. If the fragments become at all magnetic, it shows that the reducing gas, carbon monoxide, was present in that part of the flame where they were heated. Fe 2 -f- CO
the tip of the blue cone, where the heat is most intense, and diminishes toward o, but it is impossible to make a general statement of just where reduction ceases, as this depends
-f2
.

2FeO

C0

The reduction

is

strongest at

r,

both upon the

size of

the flame and strength of the blast.

y. To illustrate reduction and oxidation, select a small splinter of hematite, make sure that it is not magnetic, and then heat for an instant only in the reducing flame, so as to form FeO sufficient to make the fragment

only slightly magnetic. It should then be heated for a considerable time at a point o, Fig. 36 (beyond the point where carbon monoxide exists), until the FeO has taken up oxygen from the air, and become oxidized to Fe 2 3 ,

when the fragment

will cease to be magnetic.

Considerable care and

skill

are necessary for performing this experiment successfully. If the fragment becomes very magnetic, it will be best to start with a fresh one, for the

oxidation goes on slowly, and it will require a long time for its completion. Further, if FeO has been fused on the splinter, it will be almost impossible
surface
to complete the oxidation with the blowpipe, since, although the outer may be converted into Fe 2 3 , the air will not be able to reach the
interior

and make the oxidation complete. further illustrate oxidation and reduction, make a borax bead on g. platinum wire, as directed on p. 24; touch the bead when hot to a very small particle of pyrolusite, Mn0 2 and dissolve the latter in the borax by heating at about the point 0, Fig. 36. If the experiment is successful, the bead

To

should have a fine reddish-violet color, while if it is black or very dark, much pyrolusite was added, and a new bead should be made. The color is due to an oxide of manganese higher than MnO, and if the bead is heated
too
in the reducing flame,
less.
is

MnO

will be

formed, and the bead will become color-

In order to

oifered: Heat and then, without interruption, change the position of the blowpipe and the character of the blast in order to make a more bulky flame, Fig. 38, so that the bead may be completely protected from the oxidizing action of the
air.

a reduction of this kind, the following suggestion the bead very hot at r, Fig. 36, where reduction goes on,

make

If the colorless

bead

is

further heated, so that the air has access to

it.

USES OF FLAMES.

39

the reddish-violet color, characteristic for manganese, will again appear In making both oxidations and reductions, it is a (compare p. 93, 2). great advantage to be able to heat the substances very hot.

The Uses of Charcoal. Both reductions and oxidations are made on charcoal. For the former, the best results are obtained
by
inclining the charcoal, and directing the flame downward, so as to strike the assay a little beyond the tip of the blue cone, as

shown

in Fig. 40.

The combined

effect of the flame

and the burn-

FIG. 40.

ing charcoal gives an intense heat, and the reducing action may be made very strong. Further, many elements are volatilized, and, passing into the air, take on oxygen and deposit characteristic

coatings of oxide on the coal. For a list of the coatings and the effects of heating on charis

Chapter IV, p. 143. Roasting. This is a term which ing of substances in contact with

coal, see

often applied to the heatIt

generally results in oxidation, and is most conveniently done on charcoal. In order to roast a substance, the finely powdered material is spread out
air.

on the surface of the charcoal so as to allow free access of

is

air,

and

then heated with a small oxidizing flame, Fig. able distance beyond the tip of the blue cone.

41, at a consider-

scarcely a red Leat. If possible, the material should not be allowed to fuse, as it then does not expose sufficient surface to the air. When very
fusible minerals are to be roasted,
it is

The heat required

for roasting is very moderate

often best to

mix them

with about an equal volume of powdered charcoal, which prevents

40

USES OF FLAMES.

the material from

running together, and subsequently burns Another way is to fuse and continue to heat the material away. until the more volatile constituents are driven out, and then to

FIG. 41.

pulverize with a little charcoal, and roast carefully small oxidizing flame.

by means

of a

Eoasting

is

a very important metallurgical process, especially

in treating ores containing sulphur, arsenic, or antimony, as these elements are removed as volatile oxides, leaving oxides of the

metals which are subsequently reduced.

The following experiments will serve to illustrate some effects which may be produced by heating on charcoal:

of the

a. To illustrate the formation of a metal, take a very little powdered malachite (Cu.OH) 2 CO,, and three times as much of a mixture of equal parts of sodium carbonate and borax as a flux, moisten to a paste with water, then heat intensely, as shown in Fig. 40, until the copper fuses and collects

to a globule.
little

To illustrate the formation of a metal and a coating of oxide, take a powdered cerussite, PbC0 3 an equal volume of powdered charcoal and 3 volumes of sodium carbonate, moisten to a paste with water, then heat for some time, as shown in Fig. 40, until the lead unites to a globule and a considerable coating of yellow lead oxide collects on the charcoal. c. To illustrate oxidation or roasting, place some finely powdered pyrite s FeS a on a flat charcoal surface, spread the material out into a thin layer, and heat very gently with a small oxidizing flame, as shown in Fig. 41.
b.
,
,

thus oxidized, yielding sulphurous anhydride gas, SO, detected of Fe,0 8 , or a mixture of Fe 2 s with FeO. If the roasting is continued until the material no longer emits an odor of burning sulphur, the oxidation will be complete, or nearly so, and the residue will have the dark red color of ferric oxide.
pyrite
is
,

The

by

its

odor,

and a residue

CHAPTEK

III.

REACTIONS OF THE ELEMENTS.

For convenience

of reference, the subject matter of this chapter

has been arranged alphabetically. the common elements, however, it

In studying the reactions of may be recommended to take

in the following order, which has been chosen partly according to Mendeleeff's periodic system of the elements, and partly to bring together some of the elements which exhibit similarities in their analytical reactions :*
1.

them up

Hydrogen, p.
Lithium,

81.
90.

4.
5. 6.

Potassium, p. 105.

7.

Strontium, p. 116.

10. Zinc,
11.

p. 130.
71.

2.

Magnesium,
Calcium,

91.

8.
9.

Barium,

52. 42.

Copper,
Silver,

Sodium,

115.

58.

Aluminium,

12.

113.

* In the descriptions of tests and experiments, sizes and distances will be (riven in millimeters and centimeters quantities of powders and dry reagents in terras of the ivory spoon; and the volume of liquids in cubic centimeters.
;

Inch

Scale.
1

42
13. 14. 15.

REACTIONS OF THE ELEMENTS.

Lead,
p. 87. 93.
69.

Aluminium
28. 29.

18. Cobalt,
19. Nickel,
20.

p. 71.
96.

23. 24. 25. 26. 27.

Chlorine,

p. 67.
56.

Mercury,

Boron,
Arsenic,

Bismuth, p. Carbon,
Titanium,

54.

61. 107. 187.

Chromium,
Manganese,

Oxygen,
Sulphur,

100.
118.
75.

Phosphorus, 101.
^7. 43.

30. Silicon, 31.

16.

98.

21.

17. Iron,

83.

22. Fluorine,

Antimony,

32. Tin,

725.

Aluminium, Al.

Trivalent.

Atomic weight,

27.

OCCURRENCE. Next to oxygen and silicon, aluminium is probably the most abundant element in the crust of the earth (p. 3). It is a metallic element, occurring most frequently in the group ot silicates, while it is also found in a number of oxides, fluorides, Kaolinite, H Al Si phosphates, and sulphates, cyanite, KAlSi O Al SiO almandine garnet, Fe Al (SiO ) orthoclase, corundum, ALO, and cryolite, ]STa AlF 6 may serve as examples of its compounds. Aluminium also plays the part of a weak acid, and by some authors, spinel, MgAl O = MgO.Al O and a few similar compounds are regarded as aluminates. Aluminium is a constituent of most rocks, almost the only exceptions being the carbonates, sandstones, and quartzites. DETECTION. Igniting with cobalt nitrate is the only satisfactory blowpipe test for aluminium. For a test in the wet way, precipitation with ammonia is recommended,
4

3 ,

1.

Test with

Cobalt Nitrate.

Infusible minerals containing

aluminium,

if moistened with cobalt nitrate and intensely ignited before the blowpipe, assume a fine blue color. Cobalt nitrate on ignition yields cobalt oxide, CoO, which is black, and this oxide

unites in

some inexplicable way with the alumina

to give the

characteristic blue color.

In applying the test to very hard minerals it is best to powder them, then moisten with cobalt nitrate and heat either on charcoal or on a small loop on platinum wire.

The test is restricted to compounds which are light colored, or become so on ignition, and is not characteristic if applied to fusible minerals, as cobalt oxide may impart a blue color to any fused
material or flux.

Zinc silicates also give a blue color, p. 133.

fragments of cyanite, Al 2 Si0 6
Al.,0,.
,

Apply
and
2.

this test to

held in the forceps,

to finely

powdered corundum,

Precipitation with

Ammonia.

Ammonia, when added

in

Antimony

REACTIONS OF THE ELEMENTS.

43

slight excess to
tates gelatinous

an acid solution containing aluminium, precipi-

aluminium hydroxide, A1(OH)

with

great

many

ammonia, gelatinous precipitates resembling aluminium hydroxide, and therefore it is necessary to

other substances yield,

make
on a
tube,

the

following additional

tests

Collect

the

precipitate

filter-paper,

wash with water,

transfer

some

of it to a test-

and add potassium hydroxide, when the precipitate, if it is aluminium hydroxide, will go easily and completely into solution. Burn the paper containing the precipitate in a porcelain crucible (Fig. 27, p. 22), and test the residue with cobalt nitrate.
Dissolve an ivory spoonful of alum, KAl(S0 4 ) a .12H a O, in a test-tube in 5 cc. of hot water, add 2 cc. of hydrochloric acid, and then ammonia in slight excess; that is, until a distinct odor of ammonia is perceptible after the contents of the tube have been thoroughly mixed. Filter off the preand test as recommended above. cipitate,
3.

For

detecting

aluminium in insoluble

silicates,
p. 110,

where the
4.

above methods .cannot be directly applied, see

Ammonium,

NH

Univalent.

Molecular weight,

18.

OCCURRENCE. The radical ammonium, plays the part of a metal, and in its chemical relations is very similar to potassium. Minerals containing ammonium are of rather rare occurrence, and
4 ,

NH

Sal ammoniac, are generally soluble in water. C1, and struv.6H 2 O, are examples of its compounds. 4 4 ite,
4

NH

NH MgPO

DETECTION.

Compounds containing ammonium, when

boiled

with a solution of potassium hydroxide, or heated in a closed tube with lime (ignited calcite), yield the strong and very characteristic odor of ammonia.

Antimony, Sb.
120.

Trivalent and pentavalent.

Atomic weight,

found chiefly in combination with or as sulphantimonites, which sulphur, either as stibnite, Sb S H Sb S H Sb a S are salts of sulpTiantimonious acids, H Sb S

OCCURRENCE.

Antimony

is
2

3 ,

4 ,

6 ,

H Sb S
8 2

7 ,

etc.

The composition

of the sulphantimonites

is

fre-

quently expressed as a combination of

Sb S
2

with sulphides of

44

REACTIONS OF THE ELEMENTS.

4

Antimony

the metals, examples being, zinkenite, PbSb 2 S Pb 2 Sb 2 S 6 = 2PbS.Sb 2 S, jamesonite, pyrargyrite,

;

=
s
.

3Ag

S.Sb 3 S 3

and

tetrahedrite,
(p. 47),

Cu Sb S
e

PbS.Sb S Ag SbS =
2
3

4Cu S.Sb S
2 2

(See also

the sulpharsenites

with which the sulphantimonites are

frequently isomorphous.) Antimony also occurs native, rarely in combination with metals as antimonides, breithauptite, NiSb, and
occasionally in different combinations with oxygen, senarmontite,

Sb a

and

cervantite,

Sb 2 O

DETECTION.
ing of oxide

Antimony may usually be detected by the

reaction
is

coat-

formed by roasting on charcoal or in the open tube.

also

The closed-tube
antimony.
1.

recommended

for sulphide of

Coating of Oxide. Most antimony compounds, when heated on charcoal in the oxidizing flame, yield a dense white sublimate of oxide of antimony, which deposits quite near the heated part (compare Arsenic), and appears
bluish
if

Roasting on

Charcoal:

the coating

is thin,

so that the black of the charcoal

shows through it. The coating is due to volatilization of the antimony and its oxidation in passing into the air. It is quite
before the blowpipe either in the oxidizing or reducing flames, and may be driven about and made to change The fumes have no distinctive odor its place on the charcoal.
volatile

when heated

(difference

from

arsenic).

In the absence of other elements which

give coatings on charcoal, this test serves as a very simple and Where other characteristic one for the detection of antimony. elements (especially lead and bismuth) interfere, the open-tube
reaction will give confirmatory and decisive results. Some oxides of antimony are not volatile in the oxidizing flame, and when these are to be tested it is necessary to heat them

in a reducing flame to convert the antimony to the metallic state, so that it will volatilize and give the coatirg of oxide described above.
Place about \ ivory spoonful of Test the foregoing with stibnite, Sb 2 S 3 flat charcoal surface, and heat with a small oxidizing flame (]). 40,
. .

it

on a

41) until the material

is

completely volatilized.

Note that the sublimate

Antimony

REACTIONS OF THE ELEMENTS.

45

deposits close to the heated part (difference from arsenic), and test its The odor which may volatility in both the oxidizing and reducing flames.

he observed

is

due, not to the antimony, but to sulphur

(p. 119,

2).

Roasting in tlie Open Tube: Sublimate of Oxide. When metallic antimony and its compounds with sulphur are heated in
2.

the open tube, oxides of antimony are formed and deposit as sublimates on the walls of the tube, but the products vary somewhat with the conditions. If sulphur is present, the oxide usually

appears as a dense white smoke, and most of it settles for a considerable distance along the under side of the tube, while some
condenses as a ring rather near the heated part. The ring is Sb O and when examined with a lens will frequently be found to
of
it
2 3 ,

consist of

octahedrons and prisms, corresponding to senarmontite and valentinite, two forms of Sb 2 3 found in nature. When heated, this part of the sublimate is
crystals,

two kinds of

be driven up and out of the tube, slowly than oxide of arsenic. The white sublimate which condenses along the bottom of the tube is probcompletely volatile, and

may

although much more

ably antimonate of

antimony, SbSb0

It is

non-volatile,

in-

fusible, and becomes straw-yellow when hot, but white again when cold. In the absence of sulphur and in some compounds

containing
3

(apparently those that oxidize slowly), only the volJust why the presence of sulphur causes the atile Sb 2 O forms. formation of the higher oxide is not known, but probably its
it

oxide acts in some

way
2

as a

means

for transferring oxygen,

changing Sb

to

Sb

4.

and heating very

using about | of an ivory spoonful, on p. 19. Test also the volatility of the sublimate, and compare the reaction carefully with the correspondTo obtain the wholly volatile sublimate 2). ing one for arsenic (p. 48, of Sb 2 n , heat a little metallic antimony in the open tube.
Test the above with stibnite, Sb 2 S 3
,

carefully, as directed

3.

Heating in the Closed Tube.

many sulphantimonites, when heated

characteristic looking sublimate of

Sulphide of antimony and in a closed tube, yield a

oxy sulphide

of

antimony,

46

REACTIONS OF THE ELEMENTS.

Antimony

Sb 2 S a O.

It is volatilized

This requires "a rather intense heat for its production. with difficulty, and appears black when hot, but

changes on cooling to a rich reddish-brown. Metallic antimony cannot be volatilized in a closed glass tube, except at a very high temperature, where hard glass softens.
to this behavior, arsenic and antimony, which frequently occur together, especially in sulpharsenites and sulphantimonites, may sometimes be conveniently separated and identified, since

Owing

sulphides volatilize readily. After driving the sublimate a short way up the tube, cut off the latter a little below
arsenic
its

and

and test for the arsenic by the open- tube method (p. 48, 2). After removing the residue from the tube, test it for antimony, either before the blowpipe on charcoal, or in the open tube. To
it,

test for arsenic in presence of

antimony, see also

p. 49,

4.

Take a small fragment of stibnite in a closed tube, and heat it at a high The small, quantity of air in the temperature and for a considerable time. tube is all that is necessary to bring about the reaction shown by the
Sb 2 S 2 following equation: Sb 2 S 3 -jthe antimony sublimate. deposits beyond
tube reactions where the air
4.

slight ring of sulphur This is one of the few closedin the tube plays an important part.

+ S. A

Test with

Hydriodic Acid on a Gypsum

Tablet.

Antimony

compounds, when

treated according to directions given on p. 17, yield a beautiful red coating of iodide of antimony, which disappears when held over strong ammonia.
5.

Flame

Test.

When, antimony compounds

are heated before

the blowpipe in the reducing flame, antimony volatilizes and imparts to the flame a pale greenish color. The precautions against
alloying the forceps, mentioned on p. 15, should be observed. 6. Oxidation with Nitric Acid. When antimony or its sul-

phides are treated with concentrated nitric acid, the antimony is oxidized to metantimonic acid, SbO 2 OH (?), which is a white sub-

By diluting quite a satisfactory separation of antimony may be obtained from other substances with which it is apt to occur in combination. The material on the filter-paper may be
nitric acid.

stance, very insoluble in water

and in

with water and

filtering,

Arsenic.

REACTIONS OF THE ELEMENTS.

47

examined for antimony by heating before the blowpipe on charcoal, and the different metals in the filtrate may be precipitated by appropriate reagents. This treatment will frequently be found
convenient, especially for detecting a small quantity of antimony in pres*7 ice of arsenic.

Arsenic, As.

Trivalent and pentavalent.

Atomic weight,

75.

OCCURRENCE. Arsenic usually plays the part of a non-metallic element, and forms three important classes of compounds, the In arsenides, arsenides, the sulpharsenites, and the arsenates. the metals are united directly with arsenic as nicolite, NiAs, and
;

These compounds are analogous to the sulphides smaltite, CoAs and are often isomorphous with them. Several compounds are
a
.

known which

are

combinations of arsenide and sulphide

as

the commonest of the arsenic minerals, arsenopyrite, FeAsS = FeS 2 The sulpharsenites may be regarded as salts FeAs,

+
3

of
etc.

sulpharsenious

acids,

H As S
3 2 3 2
6

4 ,

H As S
4 2

6 ,

H,As S
3

compounds are sartorite, Examples Pb As S =2PbS.As S proustite, Ag AsS, PbS.As S dufrenoysite, = 3Ag S.As S and tennantite, Cu As S 4Cu S.As S The numof these
a 4 b ;

H As S PbAs S =
,

7 ,

3 ;

ber of Sulphantimonites, is quite large, but they are of rather rare occurrence (compare sulphantimonites, p. 43). Enargite, Cu AsS 4 = 3Cu 2 S. As 2 S is a sulphar senate or salt of sulphar senic
3
%5 ,

acid,

The

the phosphates, they are of rather rare occurrence.

of this acid are exceedingly rare. AsO are analogous to 8 arsenates, salts of arsenic acid, and although a great many of them are known,
s 4 ,

H AsS

but other

salts

4 ,

Pb (PbCl)(PO olivenite, 2H O. In addition to the foregoing

4 4) 8 ; 2
,

Examples are mimetite, Cu(CuOH)AsO and scorodite, FeAsO

4 ;

classes of

compounds, the
.

ele-

ment occurs as native arsenic, as the sulphides, realgar, AsS, and as the oxide, As 2 O orpiment, As 2 S 3 and sparingly The method that should be used for the detecDETECTION.
3

tion of arsenic depends

upon whether

or not the mineral contains

oxygen.
to

employ

With those compounds containing no oxygen, it is best an ox ition process, such as roasting on charcoal r in
v

48

BEACTIONS OF THE ELEMENTS.

Arsenic

the open tube.

Heating in a closed tube

some compounds.
reduction process.
Tests

With

arsenates

it is

a good method for necessary to employ a

is

for Arsenic in Minerals containing No Oxygen. 1. Roasting on Charcoal : Coating of Oxide : Arsenical Odor. When arsenic, its sulphide, or an arsenide, is heated before the blowpipe on charcoal, volatile products are given off, and the

oxygen of the air to form As O a white, which condenses on the charcoal at a considvolatile substance, erable distance from the assay. The fumes that are given off
arsenic unites with the
2
3 ,

heated in the reducing flame have a disagreeodor with which one soon becomes familiar, and able, garlic-like which serves as a characteristic test for the identification of the
is

when the assay

element.

perhaps due to the formation of a little arseniuretted hydrogen, AsH It does not come from As O for
is
3
.

The odor

s ,

this,

when

volatilized without reduction, gives

no odor.

The tests mentioned above may be very well observed by heating either the powder or fragments of arsenopyrite, FeAsS, on a flat charcoal surface. Note carefully that the sublimate deposits at a considerable distance from
by heating with a blowpipe flame (comIn addition to the garlic odor of the arsenic, pare Antimony, 1). the sulphur, especially after the assay has been heated for some time, yields a strong pungent odor of S0 2 (p. 119, 2), which is entirely different from
its volatility

the assay, and test

p. 44,

that of the arsenic, and must not be mistaken for

2.

it.

Roasting in the Open Tube.

When
3 ,

arsenic,

an arsenide, or

a sulphide of arsenic, is heated in an open tube, a sublimate of white crystalline arsenious oxide, As a O is formed, and condenses as a ring on the sides of the glass. The sublimate is further characterized

by being volatile, so that it can be readily driven up and out of the tube by heating. The crystals of As O develop best where the glass is rather warm, and by breaking the tube and examining them with a microscope it will be found that they are
2
3

usually simple, but occasionally twinned, octahedrons.

Heat from
FeAsS,
in

to -fa of, an ivory spoonful of powdered arsenopyrite, an open tube, and observe the reactions mentioned above.

Arsenic

[REACTIONS OF

THE ELEMENTS.
.

49

10 SFeAsS Fe 2 3 2S0 2 As 2 3 If a yellow deposit of sulphide of arsenic forms, or a black one of arsenic, it indicates that the oxidation has not been made properly; either the substance was heated too rapidly.
or there was not a sufficient draft of air passing the oxidation (see p. 19).
3.

up the tube

to bring about

Heating in the Closed Tube : Arsenical Mirror. When and some arsenides are heated in the closed tube, arsenic volatilizes and condenses on the cold walls of the tube. When
arsenic

very

little deposits,
;

cal mirror)

but

if

the sublimate appears brilliant black (arsenimuch of it is driven off, that which is nearest

to the heated end crystallizes

broken just
volatilizes,

and appears gray. If the tube is below the sublimate and heated so that the arsenic

the characteristic garlic odor

arsenic
is sufficient

distinctly, perhaps better in this

may be observed very than in any other, and a way

it.

very

little

to give

yellow sulphide of arsenic

At first, perhaps, a little Test the above with arsenopyrite, FeAsS. may be driven off, but the arsenical mirror soon
its

makes
follows

appearance.

Owing
-r As.

to the greater affinity of iron for

is

sulphur

than for arsenic, the change which the mineral undergoes

:

essentially as

FeAsS

FeS
of

arsenic, realgar, AsS, and orpiment, As 2 S 3 , when heated in the closed tube, are completely volatilized, condensing at first as

The sulphides

a reddish-yellow sublimate,

changing
cold.

to

dark red or almost black when hot,

and

to

reddish-yellow when

4.

Special Test for Oxide of Arsenic.

An

cate test, proposed

by

Berzelius,

may

be made

exceedingly by placing a

delilittle

oxide of arsenic at the bottom of a closed tube drawn out as in

and above it, a splinter of Heat is first applied at FlG 43 the upper end of the charcoal, until the latter becomes red hot, and then at the lower end, when the oxide of arsenic volatilizes, becomes reduced in passing the red-hot charcoal, and condenses above as an arsenical mirror. This method will be found very convenient for testing coatings of
Fig. 43,

charcoal.

oxides, obtained

there

is

by heating before the blowpipe on charcoal, when doubt as to whether they contain arsenious oxide. any

50
It will also

REACTIONS OF THE ELEMENTS.

Arsenic

be especially useful when

the

it

is

desired to detect

arsenic

in

presence

of antimony,

for the

two

elements

frequently occur together, and both give volatile white coatings on charcoal, but antimony oxide gives no mirror when treated as

be noted, however, that when a considerable quantity of antimony is taken, a trifling dark deposit of some antimony compound may form near the charcoal, but this
above.
It is to

should not be mistaken for the characteristic arsenical mirror, which forms a considerable distance up the tube. In order to

make

the

test, it is
is

coating which

farthest

only necessary to scrape up a little of the away from the assay (a little charcoal

powder with
above.
5.

it

does no harm), and heat in the tube as directed

Test with Hydriodic Acid on a Gypsum Tablet. Arsenic compounds, when treated according to directions given on p. 17, yield a very volatile orange to yellow coating of iodide of arsenic. If arsenic is volatilized from a mineral by heat6. Flame Test.

ing before the blowpipe in the reducing flame, it imparts to the The color may also be obtained when either latter a violet tinge.
arsenic or its sublimate of oxide in a tube
is volatilized,

so that it

passes from the end of the tube into the reducing part of a

Bunsen-burner flame. 7. Oxidation with Nitric Acid.

Compounds

of arsenic,

when
.

boiled with concentrated nitric acid, are, with few exceptions, As0 4 oxidized and dissolved, with formation of arsenic acid, 3

To

detect arsenic in the solution, the

(

methods given beyond under

ar senates

9, b)

may

be employed.

ARSENATES.

DETECTION.

The reduction

of arsenates in the closed tube,

with the formation of an arsenical mirror, furnishes the best means of detection. The oxidation and roasting processes used
for the detection of arsenic in arsenides

and other compounds

containing no oxygen cannot be applied to arsenates, as they are

already oxidized.

Arsenic

REACTIONS OF THE ELEMENTS.

51

1. Reduction in the Closed Tube : Arsenical Mirror. a. With few exceptions the arsenates are readily fusible, and for all such the following decisive test may be applied In a narrow closed tube place a few splinters of charcoal and a fragment of the
:

and heat intensely with a blowpipe flame, so that the fused mineral comes in contact with the charcoal. Under these conditions the arsenate is reduced, and the arsenic volatilizes and
arsenate,

forms an arsenical mirror.

b.

Provided the arsenate

is

infusible in the closed tube,

and in

the absence of easily reducible metals, such as lead, copper, or Mix a little of the finely powdered iron, proceed as follows
:

mineral with 4 volumes of dry sodium carbonate and a powdered charcoal, transfer to a closed tube, warm gently at

little
first,

and then heat intensely in a Bunsen-burner or blowpipe flame. Under these conditions the arsenic, resulting from the reducing action of the charcoal, will volatilize and condense on the glass as an arsenical mirror.
the foregoing tests cannot be applied, mix the powdered mineral with about 6 volumes of sodium carbonate, and fuse
c.

When

either in a platinum spoon or on a flat charcoal surface, using

an

oxidizing flame. The fused material is transferred to a test-tube, boiled for a minute with about 5 cc. of water, in order to dissolve

the sodium arsenate resulting from the fusion, and then filtered. To the filtrate hydrochloric acid is added in excess, then an excess
of

ammonia, which may cause the precipitation of some arsenate, and lastly a little magnesium sulphate solution, in order to precip-

itate the arsenic as

ammonium magnesium
of
it

arsenate,

NH MgAs0
4

4.

Filter off the precipitate,

paper,

mix a

little

dry it by pressing between blottingwith sodium carbonate and charcoal

5.

powder, and heat in a closed tube as directed in

the precipitate
is

Provided

small, place the filter-paper containing it in a porcelain crucible, char the paper by very gentle ignition, and test the charred material, mixed with a little sodium carbonate and

charcoal powder, in a closed tube.

52

REACTIONS OF THE ELEMENTS.

Barium

Barium, Ba.

Bivalent.

Atomic weight,
is

137.

OCCURRENCE.
quite

Barium
in

abundantly

an alkali-earth metal, which is found and in some regions in barite, BaSO

4
,

witherite,

BaCO

3 ,

seldom met with.

combinations containing it are It occurs in only a few silicates (hyalophane,

other

but

harmotome, brewsterite), and sparingly in the igneous rocks o( some regions. DETECTION. Usually barium may be readily detected by the flame coloration, alkaline reaction, and precipitation as barium
sulphate.

Barium gives a yellowish-green coloration to the flame, which may sometimes be intensified by moistening the assay with hydrochloric acid. The color cannot be obtained directly from silicates, and must not be mistaken for that of boron and phosphorus.
1.

Flame

Test.

Make

the experiment with barite or witherite, holding fragments in the

Make the test also by heating forceps and heating before the blowpipe. some of the powder on a platinum wire, as directed on p. 35.
the exception of the silicates and phosphates, barium minerals become alkaline upon intense A similar reaction is obtained with ignition before the blowpipe.
2.

Alkaline Reaction.

With

other minerals containing alkalies and alkaline earths.

turmeric-paper.
(p. 58,
1).

Heat fragments of barite or witherite, and place them upon moistened For the cause of the alkaline reaction, see Calcium

Barium Sulpliate. Barium sulphate, insoluble in water and dilute acids, and will be prevery cipitated, therefore, from solutions containing barium, upon the addition of a few drops of dilute sulphuric acid. The test is a
3.

Precipitation as
is

BaS0

very delicate one, and will always serve to distinguish compounds containing barium from those containing boron and phosphorus,

which may give green flame colorations. It will also serve detection of barium in' silicates and other compounds.

for the

Beryllium

REACTIONS OF THE ELEMENTS.

53

a. Dissolve ivory spoonful of witherite in 3 cc. of dilute hydrochloric acid, warm if necessary, dilute with from 10 to 15 cc. of water, and add dilute sulphuric acid, when a white precipitate will form, which is barium sulphate. This should be collected on a filter-paper, washed with

water, and tested on platinum wire, as directed under

b.

1.

To apply

this test to silicates, dissolve in hydrochloric acid

(after

previous fusion with sodium carbonate, if the mineral should happen to be insoluble, see p. 110, 4), separate the silica, precipitate barium sulphate

with sulphuric acid, collect on a small filter, arid make a flame test on platinum wire. If both barium and strontium are present, a mixed flame will be obtained, and, after moistening with hydrochloric acid, often the red of strontium will appear strongest at first, while later the green of barium may be seen. In order to obtain decisive results, it may be necessary
to

make
4.

use of a spectroscope.

Specific Gravity.

On

account of the high atomic weight of

it

barium, minerals containing

are characterized

gravities, considerably greater

by high specific than those of the corresponding

p. 118,
4).

strontium or calcium compounds (see

Beryllium, Be.
Bivalent.

Atomic weight,

9.

OCCURRENCE. Although usually regarded as a rare element, beryllium, sometimes called glucinum, Gl, is found in the common mineral beryl, Be 3 Al a (Si0 3 ) 6 and in a number of others which are not very rare; as
,

chrysoberyl, phenacite, leucophanite, helvite, euclase, gadolinite, beryllonite,

and herderite. DETECTION. There are no satisfactory blowpipe reactions for beryllium, and tests must be made, therefore, in the wet way, which requires some
skill in
a.

manipulation.

is a silicate, treat it according to directions given on 110 , 4, for the solution of the mineral and separation of silicic acid; p. then heat the filtrate from the silica to boiling, and precipitate the beryllium with ammonia, which will also cause precipitation of iron, aluminium,

If the mineral

and possibly other elements, if present. Ammonia precipitates beryllium This is hydroxide, which resembles aluminium hydroxide in appearance. filtered and washed well with water, transferred together with the paper to some vessel, and warmed with dilute hydrochloric acid in order to dissolve it. The paper is filtered off, and the filtrate evaporated carefully After coolin a casserole) until only a drop or two of the acid is left. (best a few drops of water are added to obtain everything in solution, and ing, then a little potassium hydroxide solution, a drop at a time, and just sufficient to dissolve the precipitate of beryllium hydroxide which forms at

54
first.

REACTIONS OF THE ELEMENTS.

Bismuth
least

The

solution

is

then diluted with cold water to a volume of at

any precipitate of ferric hydroxide or other material filtered off, and the filtrate boiled for a short time, when, if beryllium is present, a preThe precipitate, if collected cipitate of beryllium hydroxide will appear.
cc.,

50

on a

filter-paper

and

ignited, yields beryllium oxide,

and

this

when

ignited

with cobalt nitrate assumes a not very decisive lavender color. b. If the mineral is a phosphate, special treatment is needed. The powdered mineral is dissolved in hydrochloric acid (after fusion with sodium carbonate, if necessary); when cold, ammonia is added until a permanent precipitate forms, and then hydrochloric acid, a drop at a time, To the now nearly neutral, cold, and not until the solution becomes clear.
too concentrated solution, sodium acetate is added, and the precipitated beryllium phosphate, which may also contain ferric and aluminium phosphates, is filtered and washed. until the carbon of the paper

The
is

precipitate is next ignited in a crucible destroyed, and is then fused in platinum

with sodium carbonate, by which treatment sodium phosphate and beryllium oxide are formed. The fusion is then treated with hot water to dissolve
the sodium phosphate, the beryllium oxide is collected on a filter-paper and washed, and it is afterwards dissolved in hydrochloric acid and tested with

potassium

hydroxide, as

described under

a.

If it

is

known

that the

absent, the mineral may be fused directly with sodium carbonate, and treated like the above sodium carbonate fusion.
alkali-earth metals are

Bismuth, Bi.

Trivalent.

Atomic weight,

208.

OCCURRENCE. Bismuth plays the part of a weak basic element and also that of an acid-forming one, and is of rather rare occurrence in minerals. It is found native and as sulphide, selenide, The combinations of its telluride, oxide, silicate, and carbonate.
sulphide with sulphides of the metals, the sulpJiobismutliites, are analogous to the sulphantimonites and sulpharsenites,
reactions on charcoal

may be readily detected by its and by the iodine tests. I. deduction on Char coal to Metallic Bismuth, and Formation a Coating of Bismuth Oxide. Usually bismuth can be readily of reduced from its compounds by mixing ivory spoonful of the with about 3 volumes of sodium carbonate and powdered mineral heating on charcoal in the reducing flame. The globules of the metal thus obtained are readily fusible and are bright when in the
DETECTION.
flame,

Usually bismuth

but become covered with a coating of oxide when exposed

Bismuth

REACTIONS OF THE ELEMENTS.

55

They are brittle, and, if removed from the charcoal hammered on an anvil, they may flatten to some extent at first, and
to the air.

but cannot be beaten into a thin sheet like lead. Heated before the blowpipe, bismuth is somewhat volatile, and its vapor passing
into the air becomes oxidized, and settles on the coal as a lemon- to orange-yellow coating of bismuth oxide, which is white at a dis-

The coating may be volatilized by heating tance from the assay. in both the oxidizing and reducing flames without imparting any
color to them.

The reactions

are quite similar to those of lead,

tests.

but

may

be distinguished by the iodine

cial oxide of

the test by heating any simple bismuth mineral, or the commerbismuth, as directed above. A somewhat better idea of the bismuth coating may be obtained by removing a globule of the metal and
it

Make

heating
2.

alone before the blowpipe on a fresh piece of charcoal.

excellent test proposed by von Kobell consists in adding to a small portion of the powdered mineral 3 or 4 times its volume of a mixture of potassium iodide and

Iodine Tests.

An

sulphur (p. 26), and heating before the blowpipe on charcoal with a small oxidizing flame, when a coating is produced which is yellow near the assay, and bordered on the outer edges by a
brilliant red.

The

test

on a gypsum

plate,

made

as directed on p. 17, yields

a chocolate-brown coating of bismuth iodide, which is changed to a brilliant red by exposing for a short time to the fumes of strong ammonia. If the mineral is soluble in hydro3. Tests in the Wet Way. chloric acid, evaporate the solution until only a few drops remain, and then pour it into a test-tube about one third full of water, when a white precipitate of bismuth oxychloride, BiOCl, will form, which may be collected on a filter and tested, as in 1. If the mineral is not soluble in hydrochloric acid, dissolve in nitric, then add excess of hydrochloric acid, concentrate to a small volume and pour into
If the presence of lead is suspected, water, as directed above. dissolve in nitric and 2 or 3 cc. of concentrated sulphuric acid,

evaporate in a casserole until the nitric acid

is all

expelled, and>

56

REACTIONS OF THE ELEMENTS.

Boron

after cooling, digest with water and filter off the insoluble lead 1. To the sulphate, which may be tested according to p. 87,

add ammonia to precipitate bismuth hydroxide, and when collected on a filter, may be tested according to 1.
filtrate,

this,

Boron, B.

Trivalent.

Atomic weight,

11.

OCCURRENCE. Boron is the characteristic, non-metallic element of boric acid, H BO and its salts, the borates. The latter are not very common, borax, Na B O .10H O, being the most important. Boron is also found as a constituent of a number of silias tourmaline, axinite, datolite, and danburite. Boron cates minerals have usually been formed by the action of vapors given
3 3 ,

off

during igneous activity.

DETECTION.

Boron may be detected by the flame coloration

and the
1.

with turmeric-paper. Flame Test. Many boron minerals when heated before the
test

blowpipe impart a green color to the flame.

The

color is a rather

bright one, inclining somewhat to yellow (siskin-green), anu must not be confounded with that of barium, from which it may
readily be distinguished

by other

tests.

Minerals which do not give the boron flame

usually show
it

when heated

alone

mixed intimately with about 3 volumes of the potassium bisulphate and fluorite mixture in a Bun(p. 26), and heated rather gently before the blowpipe or sen-burner flame. The mixture is most conveniently introduced

when

their

powder

is

into the flame

by taking up a

little

of

it

on the end of a hot

plati-

num

wire or in a small loop. The hydrofluoric acid liberated by the mixture attacks the mineral, forming boron fluoride, BF and
9 ,

this gives a green flame coloration,

which

is

usually of only mo-

mentary duration.
Tests

may
4 ,

be

made with

datolite,

Ca(BOH)Si0

4 ,

or

danburite,

which give a green flame color when heated alone, and also 2 (Si0 ) 2 with tourmaline, in which case it is necessary to make use of the potassium bisulphate and fluorite mixture.

CaB

Test with Turmeric-paper. If turmeric-paper is moistened a dilute hydrochloric acid solution of a mineral containing with
2.

Cadmium

REACTIONS OF THE ELEMENTS.

57

boron, and then dried at 100

C. (on the outside of a test-tube concolor,

taining boiling water),

is

it

assumes a reddish-brown

and

this

changed to inky-black by moistening with ammonia. The test is very delicate and satisfactory, and may be applied to all boron
insoluble in acids, they may be dissolved after 3 and 4. fusion with sodium carbonate, as directed on p. 110,
minerals, for,
if

Bromine, Br.
OCCURRENCE.

Univalent.

Atomic weight,

80.

This non-metallic element is found very rarely in minthe only ones of importance being the silver ores, embolite, AgCl with The bromides, salts of hydrobromic acid, AgBr, and bromyrite, AgBr.
erals,

are mostly soluble in water. DETECTION. Many of the reactions of bromine are similar to those of
Silver nitrate precipitates silver bromide, AgBr. chlorine and iodine. "When a bromide is heated in a bulb tube with potassium bisulphate and is liberated, and may be distinguished by the red color pyrolusite, bromine of its vapor, and the formation of liquid bromine if the reaction is strong. (Chlorides and iodides when similarly treated yield chlorine gas and iodine, Silver bromide, when heated in a closed tube with galena, respectively.) of lead bromide, which is sulphur-yellow when hot, and yields a sublimate

white when cold.

For the detection of bromine

in presence of iodine, see p. 69.

Cadmium, Cd.
OCCURRENCE.
associated with zinc in

Bivalent.

Atomic weight,

112.

is a rather rare element, and is mostly found some varieties of sphalerite and smithsonite. Only one cadmium mineral is known, greenockite, CdS. DETECTION. If minerals containing cadmium are mixed with sodium carbonate and heated before the blowpipe on a flat charcoal surface in the The is readily formed and volatilized. reducing flame, metallic cadmium with the oxygen of the air, and the resulting oxide collects element unites on the charcoal as a reddish-brown coating, which is yellow distant from

Cadmium

the assay, and usually iridescent if only a little of it forms. In the presence of zinc, the foregoing method may sometimes be emto the ease with which cadmium is reduced and volaployed, since, owing It is better, however, to that of zinc. tilized, its coating will appear before from 4 to 6 ivory spoonfuls of the mineral in proceed as follows: Dissolve nitric acid, add 1 or 2 cc. of concentrated sulphuric acid, and evaporate in On cooling, add about 100 cc. a casserole until the nitric acid is removed.
cc. of hydrochloric acid, filter, and pass hydrogen sulphide the filtrate for half an hour, then filter off the precipitated gas through

of water

and 10

58

REACTIONS OF THE ELEMENTS.

Caesium

Place the paper containing the sulphide, and wash with water. of charcoal, add sodium carbonate, and heat before precipitate upon a piece the blowpipe, first with a small oxidizing flame until the paper is burned, and then in a reducing flame to obtain the coating of cadmium oxide.

cadmium

Caesium, Cs.
OCCURRENCE.
H.,Cs 4 Al 4 (SiO,) 9
,

Univalent.

Atomic weight,

133.

This very rare alkali metal has been found in pollucite,

and in small quantities in some varieties of lepidolite and Rubidium is often found with caesium. beryl. DETECTION. Caesium is similar to potassium, and may be precipitated The precipitate i caesium platinic chloride, Cs a PtCl 6 (see p. 106, as 3).

much more
tity, it is

rates in a finer condition,

insoluble than the corresponding potassium compound, sepa^ and has a paler color. To make sure of its iden-

best to heat some of the precipitate on a platinum wire, and examine the flame with a spectroscope.

Calcium, Ca.

Bivalent.

Atomic weight,

40.

OCCURRENCE.

This alkali-earth metal

is

found very abun-

dantly in nature (see p. 3). It is a constituent of many silicates and of most rocks, while its combinations with hydrofluoric, carbonic, sulphuric, phosphoric,

Examples
fluorite,

of important calcium minerals

2 ;

and other acids are very common. are calcite, GaCO,

4
;

CaF

gypsum, CaSO .2H,O

4
4 3
.

pyroxene, CaMg(SiO,) a

and apatite, Ca (CaF)(PO ) DETECTION. Usually, the best methods to apply are the alkaline reaction after heating, and the precipitation as calcium sulphate, carbonate, or oxalate. Calcium minerals 1. Alkaline Reaction.

become alkaline

upon ignition before the blowpipe, with the exception of the silicates, phosphates, borates, and the salts of a few rare acids.

similar reaction is obtained with other minerals containing

alkalies
a.

and alkaline

earths.
calcite before the blowpipe, and place it upon a In this experiment, the heat drives out

Heat a fragment of

piece of moistened turmeric-paper.

C0 2 from the calcite, leaving lime, CaO, which dissolves to some extent in the water and gives the alkaline reaction. b. Heat a fragment of fluorite, and place it upon moistened turmericpaper.
to

In this experiment, water (one of the products of combustion) reacts

fluorite, as follows-

some extent upon the

CaF 2

-j-

CaO

+ 2HF.

Calcium
Fluorite, if heated
alkaline.

REACTIONS OF THE ELEMENTS.

in

59

a closed tube, would not decompose nor become

In this exc. Heat a fragment of gypsum and test on turmeric-paper. periment, the intense heat of the blowpipe flame is perhaps sufficient to drive out S0 3 from CaS0 4 , although the water resulting from combustion undoubtedly assists very much in bringing about the decomposition (com1, where only neutral water is given off by heating gypsum pare p. 81,
in a closed tube).

2.

Flame

Test.

A few calcium

the blowpipe volatilize coloration to the flame.

compounds when heated before to some extent and give a yellowish-red The color is often weak, and in testing

most calcium minerals

does not appear at all. Since calcium chloride is volatile, the color may often be observed when the assay is heated, after moistening with hydrochloric acid. The flame must not be mistaken for the much redder one of strontium
it

(see p. 116,

1).

of calcite in the platinum forceps, and observe that it a very little or no color to the flame ; then touch it to a drop of gives only hydrochloric acid and heat again. Better still, mix powdered calcite with a drop of hydrochloric acid, then touch the end of a clean platinum wire

Heat a fragment

to the mixture,

and introduce

it

into a Bunsen-burner or blowpipe flame.

3.
4

CaS0 .2H

Precipitation as Calcium Sulphate (Gypsum). As gypsum, O, is rather insoluble in water, and sparingly so in di2

lute hydrochloric acid, it

may

be precipitated from a solution

containing calcium upon the addition of a few drops of dilute sulphuric acid, provided the solution is neither too dilute nor too
strongly acid.

given below, it tion of calcium.

out according to the details will be found a very convenient one for the detecIf the test is carried

Dissolve 2 ivory spoonfuls of calcite in a test-tube in 3 cc. of hydrochloric acid, divide the solution into 2 parts, dilute one with about 10 times its volume of water, and then add a few drops of dilute sulphuric acid to
each.

The

precipitate

which forms

in the concentrated solution

is

calcium

sulphate, and
(difference
solution,

this will dissolve readily

from strontium and barium).

owing

No precipitate forms in the dilute to the solubility of the calcium sulphate.

upon addition

of water

and warming

60

REACTIONS OF THE ELEMENTS.

Calcium

Calcium is not precipitated 4. BeJiamor toward Ammonia. from solutions upon addition of ammonia, except when carbonic, phosphoric, silicic, boric, or other acids are present with which
This behavior is very imcalcium forms insoluble compounds. portant, for often other elements which are present with calcium
in a solution

may

by

filtration,

be precipitated by means of ammonia, separated and the calcium detected in the filtrate by the tests

given beyond.
a. Dissolve an ivory spoonful of calcite in a test-tube in 3 cc. of dilute hydrochloric acid, boil for a few seconds to expel G 2 , dilute with about 10 cc. of water, and add an excess of ammonia; i.e., until the solution smells of
4

ammonia, or shows a blue color with litmus-paper.

If the calcite should be impure, traces of foreign substances may be precipitated, but no calcium Save the solution for experiments under 5 and 6. will be thrown down.

Dissolve an ivory spoonful of apatite, calcium phosphate, in a test' in 3 cc. of hydrochloric acid, dilute with water, and add ammonia in tube, In this experiment, the precipitate which forms is calcium phosexcess. and this, although soluble in acids, is insoluble in neutral or alkaline phate,
b.

solutions.

Precipitation as Calcium Carbonate. Ammonium carbonadded to a solution made strongly alkaline with ammonia If made from a boiling precipitates calcium carbonate, CaCO the precipitation is practically complete, and the calcium solution,
5.

ate

can be removed by
6.

filtering.

Precipitation as Calcium Oxalate. Ammonium oxalate added to an alkaline or even slightly acid solution precipitates calcium oxalate, CaC 2 O The test is very delicate, and the sep4
.

aration complete, but the precipitate comes down in a very finely divided condition, and is apt to run through a filter-paper. It

almost always, however, be readily filtered if the precipitation is made in a hot solution, and then allowed to stand for an

may

hour before
The

filtering.

following method

may sometimes be found convenient

for the de-

tection of calcium in phosphates: Dissolve an ivory spoonful of the powdered mineral in a test-tube in 3 cc. of hydrochloric acid, add ammonia
until a precipitate

forms, and then hydrochloric acid, a drop at a time,

Carbon

KEACTIONS OF THE ELEMENTS.

61

until the solution becomes clear. Dilute now with about 10 cc. of water, and add ammonium oxalate, when, if calcium is present, it will be precipitated from the slightly acid solution as oxalate. The above may be tested

with apatite.
7.

For

the

detection of calcium in silicates

4.

and complex

bodies, see p. 110,

Carbon, C.

Tetravalent.

Atomic weight,

12.

OCCURRENCE. Diamond and graphite are crystallized forms of carbon, and anthracite coal is also nearly pure carbon. Bituminous coal, asphalt, paraffin, mineral oils, and many natural
gases are different forms of hydrocarbons;
i.e.,

combinations of

carbon and hydrogen, for which usually no definite chemical formulae can be given, and which cannot, therefore, be classed as
definite mineral species.

The carbonates,

salts of carbonic acid,

H C0
3

form a very important

class of minerals, including

3
;

such

common ones as calcite and aragonite, CaCO and many others. siderite, FeCO
3 ,

dolomite, CaMg(CO 3 ) 2 ;

DETECTION.

The burning

of carbon with formation of carbon

dioxide, and the closed-tube reactions serve for the detection of

the different forms of coal, hydrocarbons, and organic substances. For carbonates, effervescence with acids is usually a sufficient
test.

Carbon, Anthracite and Bituminous Coals, Hydrocarbons, and

Organic Matter.
Hydrocarbons, bituminous coals, and organic matter, when heated in a closed tube, usually suffer
Closed-tube Reactions.
destructive distillation.

are given

off,

and

Tar-like substances, oils, water, and gas condense in the tube, while a strong empyreumatic

usually be observed. The residue, if any is left, is genAnthracite coal and the different forms erally nearly pure carbon. of nearly pure carbon suffer no change when heated in a closed

odor

may

tube, except that perhaps a little water is driven

a.

off.

To show

the effect of

organic matter, heat a small fragment of

wood

in a closed tube.

62
I.

REACTIONS OF THE ELEMENTS.

Partly
fill

Carbon

a bulb tube or a large closed tube with bituminous coal, ;draw out the upper end, as in Fig. 44,

then apply heat to the bulb, and

set fire

mass it would indicate a coking coalt while if soft and pulverulent, it would indicate a non-coking coal. c. Partly fill a bulb tube or a large closed tube with pyrolusite, Mn0 2 ,
cular
carefully shove a piece of anthracite coal to a position near the pyrolusite, a, Fig. 45, and apply heat, first to the
coal until
it

FIG. 44.

to the escaping gas. If the residue left in the tube forms a hard, coherent, vesiT

.,

,.

becomes red hot, then to

the pyrolusite. As oxygen is driven from the pyrolusite, the coal will burn,

^^^

a
oxygen
lasts or

and continue

to

glow

as long as the supply of

any of the

coal remains (compare p. 100, 1). Graphite is a form of carbon which burns with great difficulty, and cannot be tested as above, while diamond burns quite readily, provided that
.part of the glass
jstart

where the diamond

is

located

is

heated intensely so as to

the combustion.

(Jarbonates.
1.

Effervescence with Acids

are salts of a

When carbonates
a
,

are dissolved

in acids, carbon dioxide gas,

C0

is

given

off

with effervescence.

The carbonates

weak

acid,

and when treated with a

strong acid they are decomposed, yielding salts of the stronger, and setting the weaker acid free. Theoretical carbonic acid is

H CO
2

8 ,

but when liberated

it splits

up

into

and

CO

3.

There-

fore, the reaction between calcium carbonate and hydrochloric CaCO acid may be represented as follows 2HC1 =
:

CaCl 2

+ H O + CO
2

3.

Any

strong acid (hydrochloric, nitric, or

sulphuric) may be used to liberate carbon dioxide, by strong being meant one with strong chemical affinity, not a concentrated

The reaction usually succeeds best when chloric acid is used, and it may take place in the
acid.

dilute hydrocold, although heat has to be

sometimes

it is

necessary to apply heat.

When

applied, care

must be taken not

to mistake boiling

and escaping
is

bubbles of steam for carbon dioxide.

terized

Carbon dioxide

charac-

by being a heavy, colorless, and odorless gas, which is not aDt to be confounded with other gases. It does not support com-

Carbon

BEACTIONS OF THE ELEMENTS.

63

bustion, and,

when brought
it
2

in contact with clear

barium hydrox-

ide solution,

gives a white precipitate of barium carbonate.

CO,
a.

+ BaO H =
2

BaC0

+ H O.
2

little

Take 2 ivory spoonfuls of powdered calcite in a test-tube, add a water and an equal quantity of hydrochloric acid, when an effervescence will be observed, and the air will soon be displaced by the heavier
carbon dioxide,
if the tube is held vertically. burning match, if thrust the tube, will be immediately extinguished. Pour a little barium solution into a second test-tube, and, holding the two tubes mouth hydroxide

into

mouth, incline the one containing the carbon dioxide, so that the heavy gas can pour down into the one containing the barium hydroxide, when, on
to

shaking the
is

It latter, a white precipitate of barium carbonate will appear. evident that the test with barium hydroxide, made as suggested above, can be used only when carbon dioxide is abundantly given off and the tube is filled with the gas.

more

delicate

method

of testing with

use of a tube like the one shown in Fig. 46.

barium hydroxide is to make Fragments of the carbonate

FIG. 46.

to be tested are placed in the lower bulb, and, by means of a pipette, dilute acid is introduced, care being taken not to allow any of it to get into the

upper bulb, or on the

sides of the tube

above the

latter.

The tube being

held nearly horizontal, barium hydroxide is then introduced into the upper bulb, where a precipitate of barium carbonate will be formed by the escap-

ing carbon dioxide. Effervescence may be detected in a minute particle of mineral by bringing the latter in contact with a drop of acid on a watch-glass or in a testtube.
b.

Take some dolomite, CaMg(C0

a,

)Q

and

treat

it

under

and

it

will be observed that only a very slight or

exactly as described no effervescence

takes place in the cold, but, on warming, carbon dioxide is abundantly given off. In testing carbonates which are soluble only in hot acids, it is best to

have the mineral finely pulverized. Care must always be taken not to mistake boiling for effervescence. c. The mistake is sometimes made of testing carbonates with acids which are too concentrated, as illustrated by the following experiments: In dry

64

REACTIONS OF THE ELEMENTS.

Carbon

test-tubes treat fragments of witherite, BaC0 3 , with concentrated hydrochloric acid, and cerussite, PbC0 3 , with concentrated nitric acid, and, in both cases, there will be only a very trifling or no effervescence, owing to

the insolubility of barium chloride and lead nitrate in the respective acids. On dilution with 2 or 3 volumes of water, however, effervescence will commence, because the salts which form on the outside of the fragments
dissolve,

and thus fresh surfaces of the carbonates are constantly exposed

is

to

the action of the acids.

sometimes danger of overlooking a small quantity of a carbonate, test as follows Dissolve from ^ to i of an of sodium carbonate in 5 cc. of cold water, and add a little
d.

In order to show that there

ivory spoonful

a slight effervescence will be visible, hydrochloric acid, when no or only that carbon dioxide is soluble to some extent, and remains owing to the fact On heating, the gas makes its appearance. dissolved in the liquid.

Car Decomposition by Heating: Closed-tube Reaction. bonates when heated are usually decomposed, carbon dioxide
2.

going

delicate test

exceedingly be made by heating a small particle of a carbonmay ate in a closed tube, and testing for the presence of carbon dioxide, by bringing a little barium hydroxide solution into the
off

and oxides

of the metals being left.

An

upper end of the tube by means of a capillary pipette. The ease with which carbonates decompose depends upon the character of the metals with which the carbonic acid radical is in
combination.

Carbonates of the

metals with strong chemical

affinity, such as potassium or sodium, are not decomposed at a red heat, while those with weak chemical affinity, like iron or zinc,

decompose

at a

moderate temperature.
is

mediate position, and calcite, posed at a low red heat, but

ignition into CaO, as illustrated

Calcium occupies an interis not decomor limestone, CaCO

s ,

wholly converted by intense

familiar example of burn-

by the

ing lime.

CaCO = CaO + CO
3

2.

Make the experiment by heating a small fragment of siderite, FeC0 3 in a closed tube, and observe that the brown, non-magnetic mineral is changed to black magnetic oxide of iron, while the carbon dioxide in the tube may be detected by means of barium hydroxide.
,

Cerium, Ce.
pounds.

Usually trivalent, but tetravalent in eerie com140.

Atomic weight,

REACTIONS OF THE ELEMENTS.

In connection with cerium
it

65

will be well to consider a

number

of other

The more important of these elements, are lanthanum, La; didymium, Di; yttrium, Y; erbium, Er; and thorium, Th. This group, however, has been further subdivided, so that it now
as the

known

Rare Earth Metals.

includes gadolinium, neodymium, praseodymium, samarium, scandium, terbium, thulium, and ytterbium, but the reactions for these rare substances are so obscure and difficult that no attempt will be made to give them in

the present work.

OCCURRENCE. The rare earths are usually found associated with one another, and minerals containing essentially the cerium group (Ce, La, and
Di) are cerite, allanite, monazite, fergusonite, samarskite, tysonite, parisite, bastnaesite. The yttrium earths (Y and Er) are found especially in Thogadolinite, xenotime, yttrotantalite, euxenite, polycrase, and sipylite.

and

rium

is

found in

thorite, monazite, aeschynite, polymignite,

and thoro-

gummite. DETECTION.
acid solutions by

The

means

rare earths are all precipitated as hydroxides from of ammonium or potassium hydroxides, but this
it is

precipitation may be often omitted when absent. The precipitate when filtered and chloric acid, the excess of acid removed

known
is

that calcium

is

dissolved in water, and of the earths will be thrown

dissolved in hydroby evaporation, the residue oxalic acid added, when a precipitate of oxalates

washed

The

precipitate

when

filtered,

down, which is insoluble in oxalic acid. washed, and ignited, yields oxides of the

earths.

cc. of dilute

In order to detect thorium, the oxides are dissolved by boiling with a few sulphuric acid, the solution evaporated, transferred finally to a crucible, and heated carefully until the excess of sulphuric acid is wholly
off,

thus converting the earths into normal sulphates. The sulphuric off in a good draft, for the fumes are very irritating, and in order to regulate the heat it is best to place the crucible containing the sulphates inside a porcelain one, thus leaving an air space between, and to adjust the heat so that the outer crucible is not heated above faint redThe crucible should be covered toward the end of the operation, and ness.
driven
acid

must be driven

the heating continued until no white fumes appear when the cover is If the sulphates have been properly heated, they should be wholly raised. soluble in cold water, and thorium may then be precipitated from the dilute
solution by adding sodium thiosulphate, Na 2 S,0 3 , and boiling. The precipitate, when collected on a filter-paper, washed, and ignited, yields tho-

rium oxide, Th0 2 Zirconium, if present, will precipitate with thorium, from solutions which are too concentrated, cerium may also be precipiand,
.

tated.

To make certain, therefore, of the identity of the thorium, it will be best to convert the ignited material again into sulphate, and to repeat the precipitation with sodium thiosulphate.

66

EEACTIONS OF THE ELEMENTS.

Cerium

filtrate

In order to detect the remaining groups, the earths contained in the from the thorium are precipitated by means of oxalic acid, and

converted into sulphates, as directed above. The sulphates are then dissolved in a little cold water, and about 2 volumes of a boiling, saturated solution of potassium sulphate are added, which precipitates Ce, La,

and Di completely, as double potassium sulphates, Ce 2 (S0 4 ) s -f 3K S0 , 2 4 while Y and Er remain in solution. After standing a few hours in the cold, the precipitate may be filtered, and washed with a cold saturated solution of potassium sulphate. From the filtrate, Y and Er may be then precipitated by means of ammonium oxalate, while the precipitate containing Ce, La, and Di, may be dissolved in hot hydrochloric acid, and the earths precipitated by addition of ammonium oxalate and ammonia. The detection of the separate elements in the two groups is a difficult matter, arid is usually not very important. Ce, La, and Di almost invariably occur together, while Y and Er are usually associated with one
another.

In the cerium group, pure ignited oxide of cerium, Ce0 2 , is nearly white, as are also the oxides of lanthanum, La 2 3 , and didymium, Di 2 3 , but a mixture of cerium oxide with the latter always has a brown
If the solution of the ignited oxides in sulphuric acid is yellow, indicates cerium, and is due to eerie sulphate, Ce(S0 4 ) a After ignitthe sulphates, however, cerous sulphate, Ce 2 (S0 4 ) 3 , is formed, which ing If the oxides are dissolved in a borax bead gives a colorless solution.
color.
it
.

in

on cooling, indicates cerium.

colorless or nearly so.

the oxidizing flame a brownish-red or yellow bead, fading to yellow In the reducing flame, the bead becomes

With phosphorus

salt,

the colors for cerium in the

oxidizing flame are yellow when hot, fading to colorless when cold, and in the reducing flame, colorless both when hot and cold. When cerium
or salt solved

does not interfere, didymium may be detected by means of the borax of phosphorus beads, for when a considerable quantity is disit

reducing flames.
before the
slit

imparts to them a pale rose color in both the oxidizing and Didymium also imparts to solutions a pale rose color,
If

which may be seen when they are concentrated.

a solution

is

held

of a spectroscope directed toward a strong light, or if the oxalate precipitate is held in a strong light and examined with a spectro-

scope, dark bands may be seen interrupting the continuous spectrum, which are known as absorption bands, and indicate the presence of the

didymium group among the elements

A prominent
of the green.
related to
it

band

is

precipitated by potassium sulphate. located in the yellow, and another about the middle

Yttrium gives no absorption spectrum, but erbium and the rare earths
give a series of strong absorption bands.

Chlorine

EEACTIONS OF THE ELEMENTS.

Univalent.

67
35.5.

Chlorine, Cl.

Atomic weight,

OCCURRENCE. Chlorine is the characteristic non-metallic element of hydrochloric acid, HC1, and the chlorides. With the exception of silver, lead, and mercurous chlorides, the simple chlorides of the metals are soluble in water, and their occurrence,
therefore, as minerals is rather restricted, since they cannot occur

where water
sylvite,

is

abundant.

KC1; and

ones, cerargyrite,

Of the soluble chlorides, halite, JS"aCl carnalite, KMgCl .6H O; and of the insoluble A AgCl, are the most important minerals.
; 3

number

of combinations of chlorides with oxides or hydroxides

of the metals, called

oxy chlorides, are known, and chlorine

is fre-

quently found in combination with other acids, especially silicic and phosphoric, and is then often isomorphous with fluorine

and hydroxyl. Examples are atacamite, Cu Cl(OH) or CuCl, and pyromorphite, 3Cu(OH) sodalite, Na (AlCl)Al (SiO ) Pb 4 (PbCl)(P0 ) DETECTION. The most satisfactory tests for chlorine are pre2
3

cipitation as silver chloride, or the formation of chlorine gas. Silver chloride, AgCl, is insoluble in water and dilute nitric acid. very very delicate test may therefore be made by dissolving a chloride in water or dilute nitric acid, and precipitating silver chloride by adding a
1.

Precipitation as Silver Chloride.

few drops of a solution of

give similar reactions.
If

silver nitrate.

Bromine and iodine

is

much

chlorine

present, a white,

curdy precipitate forms, or, if a trace is present, there is at first only a bluish- white opalescence. On exposure to light, the precipitate soon acquires a violet color.
In order to apply this test to minerals which are insoluble in acids, first fuse with sodium carbonate, as directed under silicates
(p. 110,

filter if

soak out the fusion with water and dilute nitric acid, necessary, and then add silver nitrate.
4),

To
in a

illustrate this test, dissolve

cc. of

few

nitrate.

J ivory spoonful of halite (common salt) water, and then add a few drops of nitric acid and of silver NaCl Test the solubility of the 3 AgCl -j3

+ AgN0 =

NaN0

precipitate in an excess of

ammonia.

68
2.

REACTIONS OF THE ELEMENTS.

Chlorine

Evolution of Chlorine. A very satisfactory test in the dry way may be made by mixing the powdered chloride with about 4 times its volume of potassium bisulphate and a little powdered pyrolusite, MnO 2 and heating the mixture either in a bulb tube or a small test-tube, when chlorine gas will be given off, and may be recognized by its pungent odor or its bleaching action on a strip of moistened litmus-paper held inside the tube (compare
,

p. 101,

2).

Insoluble compounds, such as silver chloride or a silicate, should first be fused with sodium carbonate, the fusion pulverized,
3.

and then treated as above.

Test.

Chloride of copper is volatile before the blowpipe, giving an azure-blue and sometimes a green coloration to To use this behavior for the flame (compare Copper, p. 72, 1).

Flame

the detection of chlorine, Berzelius recommended the following treatment To a small salt of phosphorus bead add copper oxide
:

until the bead is dark

substance to

and opaque, then touch it while hot to the be tested, and heat before the blowpipe in an oxidiz-

ing flame, when chloride of copper will volatilize and impart a blue color to the flame. The test answers very well for most

not sufficiently delicate for the detection of small Bromine gives a similar reacquantities of chlorine in minerals.
chlorides,
is

but

tion.
4.

To distinguish
:

silver chloride, silver bromide,

iodide from one another, the following method will convenient Heat a fragment of the mineral and a little pure, pulverized galena together in a closed tube, and observe the color of

and silver be found very

the sublimate formed.

this fuses

Silver chloride yields lead chloride,

and

on the hot glass to colorless globules which become white when cold. Silver bromide yields lead bromide, which is sulphur-yellow when hot and white when cold. Silver iodide
yields lead iodide, which is dark orange-red when hot and lemonyellow when cold. If iodine is detected by the foregoing test,

bromine and chlorine may also be present, and, if iodine the reaction for bromine will obscure that of chlorine.

is

absent,

Chromium

REACTIONS OF THE ELEMENTS.

69

5. The detection of chlorine in the presence of bromine and iodine is not a simple matter. If combined with silver, place the material in a testtube with some granulated zinc, add dilute sulphuric acid, allow the reduction to proceed for some minutes, and then filter or decant the solution of zinc salts from the insoluble silver. Take a few drops of the solution in a

add some starch paste (a little starch boiled up with considerable and then a little, red, fuming nitric acid, when, if iodine is present, water), it will impart a deep blue color to the starch. To the blue solution add chlorine water drop by drop, which at first sets iodine free, but, when added in excess, combines with it to form a colorless compound. Continue, therefore, to add the chlorine water until the color of iodine disappears, when, if bromine is absent, the solution will be colorless, but, if present, it will be This color shows more disyellowish-red, owing to liberated bromine. tinctly when the liquid is agitated with carbon disulphide, which dissolves
test-tube,

the bromine.

For the detection of chlorine, provided bromine and iodine are present, take another portion of the solution, add silver nitrate and a little nitric acid, and then filter off and wash the precipitate, which may contain AgCl,

AgBr, and Agl. Transfer this to a beaker, treat with ammonia to dissolve AgCl and AgBr, filter from the insoluble Agl, then precipitate the silver salts from the filtrate by addition of nitric acid, and collect them on a Mix the moist precipitate on charcoal with a little more than its filter. volume of sodium carbonate, fuse before the blowpipe, cut away the fusion, treat it with hot water, filter the soluble sodium chloride and bromide from the silver, and evaporate the
Grind the dryness in a dish or casserole. with an equal volume of potassium didried residue
filtrate to

chromate, transfer to a tubulated test-tube, Fig. 47, add a little concentrated sulphuric acid, close with a

and warm, when, if chlorine is present, it forms with the chromium a red gas, CrCl 2 2 which condenses to a liquid of the same color, while bromine forms red vapors of bromine. If some of the red vapors are distilled over into a second test-tube, and are then treated with a little ammonia, the bromine will be converted
stopper,
,

wholly into colorless compounds, while the OC1 2 2 will yield ammonium chromate, which is yellow. The yellow color of ammonium chromate in the second test-tube is, therefore, a proof that chlorine was present.

Chromium,

Cr.

Trivalent and sexivalent.

Atomic weight,

52.5,

OCCURRENCE.

Chromium

is

the mineral from which nearly

all its

not a very abundant element, and commercial compounds are

70

REACTIONS OF THE ELEMENTS.

is

Chromium
is

made

chromite,

FeCrO

FeO.Cr,O

The element

found, in

small quantities, in some varieties of spinel, garnet, muscovite, is isomorphous 2O beryl, clinochlore, and other minerals where

with A1

or

Fe O
2

3.

Of the chromates,
colors

crocoite,

PbCrO

4 ,

is

the

commonest. DETECTION.

The

which chromium imparts to the fluxes

If

usually serve for its detection. 1. Test with a Borax Bead.

a very little oxide of chromium is dissolved before the blowpipe in a borax bead in the oxidizing flame, the bead will be decided yellow when hot, changing to yel-

With more of the oxide, the colors are lowish-green when cold. when hot, changing through yellow to a fine yellowishdeeper, red
green when cold. After heating in the reducing flame, as soon as the bead cools below a red heat, it assumes a fine green color, and

shows none of the yellow which

the oxidizing flame. oxidizing flame depends upon the presence of

so prominent after heating in It is probable that the color produced in the

is

the anhydride of chromic acid, salts of which are yellow or red while in the reducing flame the basic oxide Cr2 O is formed, which usually
3 ,
;

CrO

imparts an intense green color to solutions. The colors which are obN0. Test with Salt of Phosphorus. tained in the oxidizing flame with this flux are dirty green when hot,

changing to fine green when cold. After reduction, the colors are about the same as in the oxidizing flame, but not so decided.

Chromium must not be confounded with vanadium, which gives in the reducing flame almost identical reactions with the fluxes, but in the oxidizing flame differs in yielding a yellow bead with
salt of

phosphorus, which flux never acquires other than a green

color with chromium.

3. Special Tests for Small Quantities of CJiromium when Associated with other Substances which Color the Fluxes. -If the mineral is a silicate,

fuse

it in a platinum spoon with about 4 volumes of sodium carbonate and 2 of potassium nitrate, by which means an alkali chromate, soluble in Soak out the fusion in a test-tube with about 5 cc. water, will be formed. of water, filter, and, if chromium is present, the filtrate will have a yellow color. Make the filtrate slightly acid with acetic acid, filter again if neces-

Copper
sary,

REACTIONS OF THE ELEMENTS.

little

71

and add a
will form,

lead acetate,

when

a yellow precipitate of lead chro-

which may be collected on a filter, washed with water, and tested with the fluxes (compare Vanadium, p. 130, If the precipitate 2). is very small, it will be best to burn the in a porcelain crucible and paper
mate
test the residue.

If the mineral

is

an oxide

difficult to

decompose, as some kinds of spinel

or chromite, dissolve as much as possible of the very finely powdered mineral before the blowpipe in a borax bead, remove the latter from the wire, crush
3 volumes of sodium carbonate potassium nitrate, fuse in a platinum spoon, and proceed exactly as described in the previous paragraph.
it

in a

diamond mortar, then mix with 2 or

and

1 of

Cobalt, Co.

Bivalent.

Atomic weight,
is

59.

a comparatively rare element, found usually in combination with sulphur or arsenic, and generally associated with nickel and iron, with which it is isomorphous.

OCCURRENCE.

Cobalt

more important compounds are linnaeite, Co S smaltite, Co As, cobaltite, CoSAs; and erythrite, Co (AsO ) .8H O. DETECTION. The blue color which cobalt oxide imparts to the fluxes serves as a very simple and delicate means for its detection. Oxide of cobalt is soluble before the 1. Test with the Fluxes. blowpipe both in the borax and salt of phosphorus beads, imparting to them a fine blue color, which remains the same in both the oxidizing and reducing flames. The test is so delicate that
few of
its
3 4 ;
;

cobalt can be detected in the presence of a considerable quantity

of iron

and

nickel.

copper or nickel interferes with the test for cobalt, remove the bead from the wire, and fuse it on charcoal with a
granule of tin in a strong reducing flame, until the copper and nickel are reduced to the metallic state, when the flux will show
the blue color of cobalt. See also the special method for treating minerals containing
cobalt, nickel, iron,

When

and copper

(p.

97,

4).

Columbium, Cb.
Copper, Cu. pounds.

See Niobium.

Bivalent in cupric and univalent in cuprous com63.4.

is

Atomic weight,
Copper

OCCURRENCE.

widely distributed in nature and

is

72

KEACTKWS Of THE ELEMENTS.

Copper
its

found in a great many minerals.

A
2
;

few of

most important
a
;

compounds

are chalcopyrite,

Cu FeS
s

8 ;

tetrahedrite,

CuFeS chalcocite, Cu S bornite, essentially Cu Sb S malachite, (CuOH) CO,;

8 2
7 ;

and

cuprite,

Cu

a O.

Copper

also occurs in the native state abun-

dantly in a few

localities.

The flame of metallic copper, and the

DETECTION.
tions
1.

coloration, the formation of globules colors imparted to fluxes and to solu-

make the detection of copper a very easy matter. Flame Tests. If finely divided oxide of copper

is

intro-

duced into a colorless flame, it imparts to it an emerald-green color, which may sometimes be observed on heating minerals before the blowpipe, but often no color is obtained because no volatile com-

pound

of copper is present.

If the

assay

is

moistened with hydrois volatile,

chloric acid, however, copper chloride,

which

will

be

formed, and usually on the outer edges with emerald-green, due to the decomposition of the chloride and formation of copper oxide. The flame
test for

this gives a strong azure-blue color to the flame, tinged

copper after moistening with hydrochloric acid is very delicate, but if the mineral is a sulphide, it should be fused in the oxidizing flame or roasted before applying the acid.
a. Take a piece of chalcopyrite in the platinum forceps, heat it before the blowpipe in the oxidizing flame, then touch it to a drop of hydrochloric The copper chloride soon volatilizes, but the flame acid, and heat again.

may be The

repeatedly obtained by renewed applications of acid. test may also be made on platinum wire, according to directions

given on p. 35. b. Roast a little powdered chalcopyrite on charcoal, as directed on p. 39. then moisten the product with a drop of hydrochloric acid, and heat before
the blowpipe in the reducing flame. In this experiment, the azure-blue flame of copper chloride is obtained in great perfection, and the surface of the charcoal near the assay will show the copper reaction if touched with the reducing flame. A beautiful emerald-green flame is obtained if the assay is moistened with hydriodic instead of hydrochloric acid, and heated
before the blowpipe. color given by oxide of copper, c. In order to show the green flame take a little malachite or cuprite in a diamond mortar, and pulverize it by
striking with a

hammer

in close proximity to a

Bunsen-burner flame, so that

the fine dust from the mortar will pass into the flame.

Copper
2.

REACTIONS OF THE ELEMENTS.

73

Reduction on Charcoal to Metallic Copper. From copper oxides and minerals containing oxide of copper, the metal may be readily reduced and obtained as fused globules by heating
intensely in a reducing flame, with a flux, on charcoal. Copper globules are bright when covered with the reducing flame, but acquire a coating of black oxide on exposure to the air. They are
malleable, can be flattened

by hammering on an anvil, and show the red color characteristic of copper. The best flux to use is a mixThis serves to ture of equal parts of sodium carbonate and borax keep iron and other difficultly reducible metals in solution, as in a slag, while copper may easily be reduced and fused to a globule.
:

Minerals containing sulphur, arsenic, or antimony should

first

be

mixed with the appropriate

carefully roasted, according to directions given on p. 39, then flux, and reduced. It is evident that,

when

other readily reducible metals are present, a globule will be obtained which is not pure copper.
difficulty in fusing copper on charcoal, it is best to use only a small quanbefore the blowpipe About i to i ivory spoonful of the tity of the mineral and flux.

As beginners usually have some

mineral and two or three times as

suitable quantity.

much

flux will be found to be a

Obtain globules of copper from malachite, using a mixture of sodium carbonate and borax as a flux, and from chalcopyrite, which must first be roasted and afterwards fluxed with a mixture of sodium carbonate and borax,
3.

Reactions with the Fluxes.

salt of

both in the borax and

Copper oxide dissolves readily phosphorus beads on platinum wire.

In the oxidizing flame, the colors are green when hot, but change to blue when cold. The color is due to the presence of cupric oxide, In the reducing flame, the colors are paler, almost colorless, with little copper while if much is present, there is a separation of cuprous oxide, Cu O, when the
test is very delicate.
;

CuO, and the

fluxes solidify,

which renders the beads opaque and red by reflected A still better way to show this reduction is to remove the light. bead from the wire, and, placing it on charcoal with a small grain of tin, to fuse the two together in a reducing flame. The bead

74

KEACTIONS OF THE ELEMENTS.

Copper

will then be clear and nearly colorless when hot, but opaque and red on solidifying. The action of the tin is to take oxygen from the cupric oxide, changing it to cuprous oxide. The reaction suc-

ceeds best with the salt of phosphorus bead, and the heating on charcoal in either case must not be too hot nor continued too long a
time, as the copper
4.

may

thus be reduced to the metallic

state.

Color of Solutions : Test with Ammonia. If a mineral containing copper is dissolved in an acid (usually nitric or hydrochloric is best), the solution will be colored blue or green. On dilution

with water and addition of ammonia in excess, the color becomes deep blue, owing to the formation of a complex cuproammonium
salt. The test is a very good one for copper, but the color must not be confounded with the similar but much fainter blue given

by

solutions containing nickel

when

similarly treated.

a. To make this test, dissolve ivory spoonful of malachite in a testtube, in 3 cc. of hydrochloric acid, dilute with 10 cc. of water, and add excess of ammonia.
b. Dissolve -J ivory spoonful of powdered chalcopyrite in a test-tube, in 3 cc. of nitric acid, boil until red fumes cease to appear, dilute with 10 cc. In this experiment, the formation of of water, and add ammonia in excess.

a precipitate of ferric hydroxide (p. 87, 5) may at first prevent the blue color from being seen, but by allowing the precipitate to settle, or better by filtering it off, the color shows distinctly.

Besides the sulphides and the closely related arsenides, tellurides, and selenides, there are very few minerals which are cuprous compounds, cuprite, Cu 3 0, being the only
5.

Cuprous Compounds.

common

one.

the only means available for proving that, in combinations with sulphur, copper exists in the cuprous If it is demonstrated, for example, that the atomic condition.
ratio of copper to sulphur is 2
:

A quantitative analysis is

1 (see p. 6), the

compound must

be Cu 2 S, or cuprous sulphide.

To
ful of

illustrate the reactions

of cuprous oxide, dissolve an ivory spoon-

in 3 cc. of hot hydrochloric acid. Observe that the solution is nearly colorless or brown, and not blue, as with cupric com-

powdered cuprite

pounds.

Cool the liquid, and then add a large excess of cold water,

when

Fluorine

REACTIONS OF THE ELEMENTS.

75

a white precipitate of cuprous chloride, CuCl, will be thrown down, which is only sparingly soluble in water and dilute acids. The precipitate is soluble
in excess of

ammonia, and,

if

color characteristic of cupric compounds some of the copper may have become

oxidation has been avoided, the intense blue ( 4) will not be obtained, although

changed to the cupric condition,

owing

to the oxidizing action of the air.

Didymium,

Di.

Trivalent.

Atomic weight,

142.

Erbium, Er.
The

Trivalent.

Atomic weight,

166.

reactions of these rare earth-metals are given under Cerium.

Fluorine, F.

Univalent.

Atomic weight,

19.

OCCURRENCE. Fluorine is the characteristic non-metallic element of hydrofluoric acid, HF, and the fluorides. The number
of
fluorides that have been identified as minerals is not very
fluorite,

large,

important.
silicates
3

and cryolite, ]S"a AlF being the most Fluorine is found frequently as a constituent of
2
;

CaF

and phosphates, as
2
4)2 ;

in topaz,
4

(AlF) 2 Si0
4 3
;

chondrodite,

Mg [Mg(F.OH)] (SiO
4 ,

Ca (CaF)(PO ) and amblygonite, in such compounds, hydroxyl and occasionally Li(AlF)PO and, chlorine are isomorphous with, and partially replace, the fluorine. DETECTION. The etching of glass and the formation of volatile compounds with silicon furnish the best methods for the detection
apatite,

of fluorine.

Etching of Glass. This test is applicable only to compounds, other than silicates, which are decomposed by sulphuric If without a platinum crucible, prepare some small pasteacid. board trays or box-covers by placing them in melted paraffin and
1.

allowing them to remain until the paper

is

thoroughly permeated;

then, leaving several drops of paraffin in the bottom of each, place them to one side on a sheet of paper to cool. At the same time

some pieces of window

glass, larger

than the tops of the boxes,

may

be coated with paraffin by dipping them in the melted

material and allowing them to cool. To make a test for fluorine, in a platinum crucible or one of the prepared trays put an ivory spoonful of the finely powdered mineral and 3 or 4 drops of concentrated sulphuric acid,

mix the two together and cover with one

of

76

REACTIONS OF THE ELEMENTS.

Fluorine

the prepared glass plates on the under side of which lines have been traced through the paraffin with some pointed instrument. The action of sulphuric acid on the fluoride liberates hydrofluoric

HF, which attacks the silica, Si0 of the glass wherever it is not protected by the paraffin; thus, 4HF + SiO, = SiF + 2H O. For a successful experiment the etching should be allowed to proceed for at least one half hour, or longer if the amount of fluorine The presence of fluorine is revealed by a distinct etchis small. ing of the glass, seen best after warming the plate and cleaning off
acid,
2
,

sulphuric acid

CaF + H S0 = CaS0 + 2HF. may This test is applicable 2. Test with Potassium Bisulphate. to compounds which are decomposed by fusion with the only reagent. Mix some finely powdered fluoride with an equal volume
be expressed as follows
:

the paraffin with a bit of paper or cloth. Make the experiment with fluorite, CaF a when the decomposition with
,

powdered glass and 2 or 3 volumes of potassium bisulphate, then put not over \ ivory spoonful of this mixture in a closed tube The hydrofluoric acid of 6 mm. internal diameter and heat gently. liberated by the reaction attacks the glass, 4HF + SiO = SiF 2H,O, and at the place where the water condenses a second decomof
a 4

position occurs, as follows

silicic acid)

3SiF

+ 2H O = 2H,SiF
a

(hydrofluo-

+ SiO,.
which

The separated silica,

is volatile

SiO.,

forms a white ring

in the tube,

as long as hydrofluosilicic acid is

present, but on breaking the tube just above the fusion and washing away the hydrofluosilicic acid from the upper portion with

water,

and then drying, the

silica will

no longer be

volatile.

The

etching of the tube is not a conspicuous feature of this test, but the ring of silica is very characteristic, especially its behavior before and after washing with water.
3.

Test with

Sodium Metaphosphate.
it

This test will often be

found convenient, since decomposed mixed with from 4 to

can be applied

to

minerals which are not

~by sulphuric acid.

If the finely

powdered mineral

is

sodium metaphosphate, transferred to a bulb tube (which should not be more than one quarter full) and heated very hot, hydrofluoric acid will be given off, which etches the glass, and deposits a ring of silica exactly as described
6 parts of

Fluorine

REACTIONS OF THE ELEMENTS.

77

-in

2.

The

fluorine is

quantities

when the proportion of not too small (less than 5 per cent), but when very small are to be detected the method given in 4 is preferable.
test is excellent for silicates

Sodium metaphosphate may be prepared by heating phosphorus salt in a platinum dish until ammonia and water are expelled, or a sufficient quantity for an experiment may be quickly made by fusing beads of phosphorus salt on platinum wire, and crushing them in a diamond mortar. To make the experiment, test for fluorine in topaz. The reaction with topaz
cannot be expressed by a definite equation, but in order to illustrate the chemical principle involved, the simpler case of calcium fluoride, CaF 2 , may = CaNaP0 4 2HF. It is evident that be chosen. CaF 2 -f- NaP0 3 -f 2 water orhydroxyl must be present in order to form HF, and this may come either from hydroxyl in the mineral or from a trace of water that was not

wholly driven out from the sodium metaphosphate.

Precipitation as Calcium Fluoride. This test is especially applicable for detecting small quantities of fluorine in silicates.
4.-

The mineral
described

is

first

under

silicates

fused with sodium carbonate, exactly as The fusion is then (p. 110, 4).

pulverized, treated in a test-tube with 5 cc. of boiling water, filtered and washed, by which means sodium fluoride is obtained in solu-

with hydrochloric acid, boiled for a short time to expel carbon dioxide, a little calcium chloride added (some calcite dissolved in hydrochloric acid will answer), and then
tion.
filtrate is acidified

The

ammonia

in excess.

The

precipitate will contain calcium fluoride,

but a precipitate is not a proof that fluorine is present, for other compounds may be thrown down at this point. The precipitate must
be collected on a
filter-paper,
is

washed well with water, and ignited in

2.

a crucible until the paper

due
1,

is

tested according to

completely destroyed, when the resiIt is not safe to test according to

for sometimes

considerable silica

calcium fluoride, and silica from the precipitate instead of etching the glass. 5. Acid Water in a Closed Tube. Most minerals containing fluorine and hydroxyl yield acid water in the closed tube, which

is precipitated with the in that case the hydrofluoric acid will derive

reddens blue litmus-paper, and when the reaction is strong the Unless the glass is etched, however, glass is distinctly etched.

78

REACTIONS OF THE ELEMENTS.

ld

a proof of the presence of fluorine must be obtained by testing according to some of the foregoing methods. In cases where
isomorphous with hydroxyl, hydrofluoric acid will sometimes be given off instead of water. The acid then etches the glass, forms a deposit of silica, and gives a strong pungent
fluorine is

smell at the end of the tube.

From

Brazilian topaz, for example,

which on analysis yields

indication of water, but,

2.5 per cent of water, the

is

hydrogen
scarcely

is

mostly expelled as hydrofluoric acid, and there

if

any

freshly ignited lime or magnesia is mixed with the mineral in the closed tube, the fluorine will be

retained and water driven

off.

Gallium, Ga.

Trivalent.

Atomic weight,

69.8.

OCCURRENCE.
sphalerite from, a

This exceedingly rare metal has been found in traces in few localities. It is best detected by means of the spark

spectrum.

Germanium, Ge.

Tetravalent.

Atomic weight,

72.3.

OCCURRENCE. This very rare element has been found in argyrodite, Ag 8 GeS 6 canfieldite, Ag8 (SnGe)S e in which tin and germanium are
; ,

isomorphous, and in small quantity in the rare mineral euxeuite. DETECTION. When argyrodite is heated before the blowpipe on charcoal, germanium volatilizes, and gives at first a pure white coating of oxide near the assay, which on prolonged heating moves farther out and assumes When examined a greenish to brownish but mainly lemon-yellow color. with a lens, the coating presents a glazed or enamel-like surface, while

scattered about on the charcoal near the assay, fused, transparent to milkwhite globules of germanium oxide may be detected.

In the closed tube, heated intensely before the blowpipe, a slight sublimate of germanium oxide forms, pale yellow when hot, becoming lighter on cooling, which with a lens may be seen to consist of numerous
colorless to pale yellow globules.

Germanium gives no reaction in the open tube. It also imparts characteristic color to the flame, to the fluxes, or to its solution in acids.
Glucinum, G.
Goid, Au.

no

See Beryllium.

Univalent and trivalent.

Atomic weight,

197.3.

Gold occurs usually in the free state, that is, as native which always contains some silver and sometimes traces of copper and gold,

OCCURRENCE.

Cold

REACTIONS OF THE ELEMENTS.

79

iron. Native gold from California generally contains about 88 per cent of the pure metal. Gold is found disseminated in small quantity in the rocks of some regions, especially the crystalline schists. It is often concentrated in veins, where it is usually associated with quartz and pyrite, and it

collects in the sands and gravels which have resulted from the disintegration of rocks and mountain masses that have contained gold. Owing to its

not form very stable compounds, and the found in chemical combination in nature is tellurium. Petzite, sylvanite, krennerite, and calaverite are tellurides of gold and silver, and nagyagite is a telluride and sulphide of lead and gold. DETECTION. The color, fusibility, malleability, high specific gravity, and insolubility in any one acid are characters which serve for the ready
affinity it does
it
is

weak chemical

only element vith which

detection of native gold. As gold is worth $20.67 a troy ounce, only a small percentage of the metal is needed to make an ore very valuable. One per cent would be equal to 291.66 troy ounces a ton, worth $6028. An ore containing yi^ per

cent of gold would be a rich one, and under favorable conditions, by hydraulic mining, gravels are washed which do not carry over ten cents

worth of gold a ton, or

present in very small quantity, even less than j^Vo- ^ one P er cent, it may be usually detected with great ease by washing or panning. This process consists in washing away with water the lighter rock constituents (for the most part
is

Washing and

than T oVo o~ f one P er cent When gold Collecting in Mercury.

less

the P ure metal.

less than 3 in specific gravity) from the gold, which varies from 15 to 19.3 in specific gravity, according to the proportion of silver it contains. In order to make the test, select a sample of the ore weighing at least a

pound, pulverize it, and sift the material through a fine sieve. At the end of the operation, care must be taken to look for particles of gold on the The powder, sieve, for, being malleable, the particles are not pulverized.

on the sieve, if there is any, are put in a metal pan, \ cc. added, and the pan is immersed in water and agitated for some time with a rocking and twisting motion, by which means the heavy gold goes rapidly to the bottom, while the lighter constituents arrange themselves above according to differences in specific gravity. From time to time the pan is inclined, and by a little motion a ripple of water is made

and the metal

is

left

of mercury

to pass over the contents of the pan, and carry off some of the lighter material from the top. By continuing this process, the material is finally concentrated so that the gold is contained in a very small volume, and is

taken up by the mercury at the bottom of the pan. To get rid of the last of the rock material, the contents of the pan are transferred to a mortar, and ground in a stieam of water, by which treatment the fine particles are rapidly carried away, and finally only the mercury, with which the gold
has amalgamated, is left. In order to obtain the gold, the mercury containing it is dried with blotting-paper, transferred to a shallow cavity on char-

80
coal,

REACTIONS OF THE ELEMENTS.

and
volatilized by heating with a small blowpipe flame.

Helium

The

residual

gold

may

when

be fused to a globule, using a little borax or sodium carbonate In order that no ill effects may result from the poisonous necessary.

FIG. 48.

mercury vapors, a piece of wet blotting-paper should be placed on the charbeing taken not to wet the cavity, and another piece arched over it (Fig. 48), thus furnishing a large cooling surface upon which the mercoal, care

cury will condense.

When tellurides are to be tested, the powdered ore should be roasted and then washed as directed above. The roasting may be accomplished by iron pan (a piece of sheet iron with the edges turned putting the ore in an
stir

up) and heating it to faint redness in a stove for some time. It is w^ll to the powder occasionally with an iron wire. Gold may be washed or panned without the use of mercury. After washing away the lighter material the particles of gold may often be seen
collected in

on the bottom of the pan as a "color." The metallic particles may be mercury and treated as directed in the foregoing paragraph, or the concentrated material may be fused with, test lead and borax, and treated as directed under the silver assay,(p. 114, 2).

The gold globules obtained by the foregoing processes will always contain some silver. In order to obtain the pure gold, the metal should be
fused with about 3 times
its

weight of pure

silver,

and then treated

in a

porcelain dish or capsule with a little warm nitric acid, which dissolves the silver and leaves the gold as a brownish-black powder or dark coherent

mass.

finely divided gold

This process of separating gold from silver is called parting. The may be washed and finally collected and fused into a

globule on charcoal.

In exceptional cases, platinum or some of the metals of the platinum group may be found with the gold.

Helium, He.

Atomic weight,

4?.

it

This element has been recently discovered, and seems to be present only in minerals containing uranium, tho-

OCCURRENCE.

rium, and yttrium. It is given off as a gas when minerals containing it are heated or are dissolved in sulphuric acid. It is detected by means of the spark spectrum.

Hydrogen

REACTIONS OF THE ELEMENTS.

Univalent.

81
1,

Hydrogen, H.

Atomic weight,

Hydrogen is found abundantly in nature in combination with oxygen as water, and in combination with carbon in hydrocarbons (p. 61). There are many minerals which
OCCURRENCE.
crystallize

with a definite quantity of water, known as water of This water constitutes a part of the chemical crystallization.
is

molecule, and
is

always expressed in the formula.

Thus,
2

gypsum

CaS0 .2H
4

]N"a 2

C0

and it contains 21 per cent of H O; natron is .10H 0, and it contains 63 per cent of H O. Such min2

O,

erals are called

anhydrous.
it is

It is characteristic of

hydrous, while those containing no water are water of crystallization that

expejled from a mineral by very gentle ignition, always at a temperature far below a red heat and frequently below 100 C.

Again, there are minerals containing the univalent radical liy

droxyl, brucite
ite is

OH, which are known as liydr oxides. For example and limonis magnesium hydroxide, Mg(OH) or Mg0 H Fe (OH) when heated a ferric hydroxide, Hydroxides
a 2 2
,

yield water.
ite,

Thus, brucite,
6 2
3

Mg(OH)
2

= MgO + H 0,
2

and limon-

Fe O (OH)
4 3

= 2Fe O + 3H O,

but

it is

characteristic for hy~

droxides that they must be strongly Jieated, sometimes to a white heat, before they are decomposed and water is given off. They thus differ from compounds containing water of crystallization.

Water of Crystallization and Hydroxyl.

DETECTION.
tube reaction.
1.

Water

is

readily detected

by means

of the closed-

Closed-tube

Reaction.

Minerals

of crystallization or

hydroxyl, when heated

containing either water in the closed tube,

yield water, which collects on the cold walls of the tube.

is

The

test

very delicate, and usually pure

is

distilled

water

is

obtained

which
a.

neutral to test-papers.

To illustrate this reaction, heat gypsum or brucite in a closed tube, fragments about 2 to 4 mm. in diameter, and also make one experiusing ment with a minute fragment, in order to show the small quantity of water which may be detected by this means.

82
b.

REACTIONS OF THE ELEMENTS.

Iodine

To

illustrate

the difference between water of crystallization and

hydroxyl, take two closed tubes of equal size, place some gypsum in one and brucite in the other, and then, holding the tubes side by side, pass them back and forth through a small flame so as to heat the ends slowly

In the tube containing gypsurn, water is driven off when the equally. temperature is scarcely above 100 C., while brucite does not yield water until the temperature is much higher.

and

Acid Water in the Closed Tube. Hydrous compounds of the weak basic elements, such as iron, aluminium, copper, and
2.

with volatile acids, are decomposed on strong ignition, yielding acid water (compare the tests for Fluorine, p. 77, 5, and for a sulphate, p. 123, 3).
zinc,
excellent closed-tube experiment may be made with copperas, FeS0 4 . 0, which it is well to compare with that of gypsum. 3 By heating very gently, only neutral water is driven off at first, but on stronger ignition the

An

7H

giving SO,, which

A secondary reaction also sets in, decomposed into FeO and S0 3 S0 2 may be detected by its odor. 2FeO + S0 3 = Fe 2 3 Both S0 3 and S0 3 , the anhydrides of sulphuric and sulphurous acids,
FeS0
4

is

render the water in the tube strongly acid. The strong basic elements, such as sodium, potassium, calcium, strontium, and barium, form stable sulphates, that is, sulphates which are not decomposed except by intense
ignition, tube.
3.

and which do not part with

their acid constituents in a closed

Alkaline Water in the Closed Tube.

it

alkaline water are of rare occurrence, but

Minerals which yield is sometimes obtained

from those containing ammonia.

Indium, In.
Trivalent.

Atomic weight,

113.3.

OCCURRENCE.

This exceedingly rare metal has been found in small

quantity in sphalerite from a few localities. Its presence is revealed by the blue color it imparts to non-luminous flames, and these when examined

with the spectroscope show an intense indigo-blue and a less intense

violet line.
I.

Iodine,

Univalent.

Atomic weight,

127.

Iodine is rarely met with, and the only known minerals are iodyrite, Agl; marshite, CuI; and lautarite, Ca(I0 3 ) Q containing DETECTION. The reactions of iodine are similar to those of chlorine

OCCURRENCE.
it

and bromine (see which differs from

Silver nitrate precipitates silver iodide, Agl, 67). silver chloride and silver bromide in being almost insolp.

Iron

EEACTIONS OF THE ELEMENTS.

83

uble in ammonia.

With potassium bisulphate

is
is

in a bulb tube, either with

its

or without pyrolusite, iodine violet vapors, or, if the reaction

Silver iodide

liberated,

and may be recognized by

its

when heated
cold.
Ir.

of lead iodide, which

strong, by in a closed tube with galena yields a sublimate is dark orange-red when hot, changing to lemon-

crystallization in the tube.

yellow

when

Iridium,
Iridium
Iron,
is

Trivalent and tetravalent.

Atomic weight,

193.

one of the rare metals occurring with platinum

(see p. 104).

Fe.

Bivalent in ferrous and trivalent in ferric com56.

pounds.

Atomic weight,

OCCURRENCE. Iron is found very abundantly in minerals is made (p. 3), and those from which most of the metal of commerce Fe O (OH) and are magnetite, Fe O limonite, hematite, Fe O Iron is found in a great variety of combinations FeC0 siderite, with sulphur (pyrite, FeS, pyrrhotite, Fe n S 12 and chalcopyrite, CuFeS ), and among the salts of most of the mineral acids, sili3 4
;

3 ;

6 ;

cates,

phosphates,

two

classes of

important to distinguish between the ferrous containing bivalent, and compounds,

etc.

It is

the ferric containing trivalent, iron.

Examples

of ferrous com-

pounds are

Fe<g>Si<g\ A1
siderite,

Fe<g>C = 0;
Li-0

almandine garnet,

Fe< o >Si <Q

;and A1

Fe<g>Si<g>
triphylite,

and of ferric compounds:

Ca<g>Si<g\Fe
hematite,

Fe=0
/Ov Fe^ (A As

>Q

andradite garnet, Ca <

Q > Si < Q C) ,O^Fe Ca<Q >Sl< O/

.

and

scorodite,

O.2H

O.

84

REACTIONS OF THE ELEMENTS.

Iron

Many minerals contain = FeO + Fe O ite, Fe,O

4
a

both ferrous and

Ferrous iron

ferric iron, as
is

magnet-

3.

very often isomor-

phous with the bivalent metals, magnesium, manganese, zinc, cobalt, and nickel; and ferric iron, with the trivalent metal
aluminium.

The magnet will usually serve for the detection of iron, while more delicate tests can be made with the fluxes or in the wet way with potassium ferri- and ferrocyanides. 1. Test with a Magnet. Only a few of the minerals containing iron (magnetite and pyrrhotite) are attracted by the ordinary magnet,* but many of them, especially the sulphides, oxides, and carbonates, become magnetic after being heated before the blowDETECTION.
pipe in the reducing flame, either on charcoal or in the forceps. When thus heated, silicates and phosphates become magnetic only when they contain a rather large percentage of iron, but the
test 'is rendered

more

delicate

if

the powdered mineral

is

fused on

charcoal with about twice its volume of sodium carbonate, and the resulting slag tested with a magnet. magnet will not attract a piece of red-hot iron, and fragments of minerals that have been heated will not be attracted

until they have

become

cold.

a. Illustrate the above by testing fragments of pyrite and hematite with a magnet, both before and after heating in the reducing flame (compare

experiments e and f on p. 38). b. Test almandine garnet with a magnet, after fusing before the blowpipe, and also test the slag made by fusing the powdered mineral with sodium carbonate on charcoal.
2.

Test with the

Borax Bead.

The oxides

of iron are soluble

in borax, and give colors which depend upon the amount of material in solution and the state of oxidation of the iron. In the

oxidizing flame, the bead contains

is

Fe O
a

and with

little

oxide

it

yellow (amber-colored)

when

hot, fading to nearly colorless

* An electromagnet, arranged with its poles close together so as to give a concentrated field, attracts all minerals containing iron, unless the percentage of the

metal

is

small.

\ron

REACTIONS OF THE ELEMENTS.

85

when cold, while with more oxide it is brownish-red when hot and yellow when cold. In the reducing flame, the bead contains and the colors are not so intense, with FeO, or FeO with Fe Mttle oxide, being pale green when hot, colorless when cold; and 'frith more oxide, bottle-green when hot, changing to a paler shade
a 8 ,

on cooling.
3.

Test with the Salt of

little

Phosphorus Bead.
c.olor is

In the oxidizing
hot, changing brownish - red,

Hame with
to colorless

oxide, the
cold,

yellow when
oxide,

when

and with more

In the reducing changing through yellow to nearly colorless. flame with little oxide, the color is pale yellow when hot, fading

through pale green to colorless, and with more oxide, brownish-red when hot, changing on cooling to yellowish-green, and finally to
nearly colorless

oxide was used, to a very pale violet. With the 4. Special Tests for Ferrous and Ferric Iron. and a few rare combinations, if exception of the sulphides minerals are dissolved in hydrochloric or sulphuric acid, the
or, if

much

solution will contain the iron in the same state of oxidation as

it

existed in the original substance.

carbonate,

For example,

siderite,

ferrous

and hematite, ferric oxide, when dissolved in hydrochloric acid, yield ferrous and ferric chlorides, respectively. H C0 3 and Fe O + 6HC1 = FeC0 + 2HC1 = FeCl
3 8

2FeCl,-f

3H 0.
2

be detected by adding potassium ferricyanide to the cold, dilute, acid solution, when a deep blue precipitate of ferrous ferricyanide will be formed, which does

Ferrous Iron.

This

may

not differ in color from Prussian blue.

3FeCl 2

+ K Fe (CN) =
6 2 12

Fe Fe (CN)
3

12

6KC1.

In solutions containing ferrous salts, potassium ferrocyanide produces Fe 2 (CN) 6 , which by absorption of a pale bluish-white precipitate of 2 from the air speedily acquires a blue color. Ammonium sulphooxygen

cyanate causes no coloration in solutions of ferrous

entirely free

salts,

provided they are

from

ferric

compounds.

Ferric Iron.

This

may be detected by adding potassium ferr o*

solution,

cyanide, to the cold, dilute, acid

when a deep blue

86

BEACTIONS OF THE ELEMENTS.

Iron

precipitate of ferric f errocyanide, or Prussian blue, will be formed.

3K 4 Fe(CN). = Fe Fe (CN) 18 12KC1. 4FeCl Addition of ammonium sulphocyanate, NH CNS, produces, even in dilute solutions of ferric salts, an intense blood-red color,
3

but no precipitate.
Potassium ferricyanide deepens the color of solutions containing ferric
salts,

but

fails to

produce a precipitate.

a.

Conversion of Iron from One State of Oxidation to the Other. Ferrous iron may be converted to ferric by boiling the hydro-

few drops of nitric acid. The reaction is a rather complicated one, but in principle it is simple. Nitric acid furnishes oxygen, and the change may be indicated as follows
chloric acid solution with a
,

2FeCl
b.

+ 2HC1 + O = 2FeCl + H O.
3 2

may be changed to ferrous by boiling the hydro chloric acid solution with metallic tin or zinc until the yellow color
Ferric iron
entirely disappears (see p. 26).
Prepare a solution containing ferrous iron by dissolving -J ivory spoonful of powdered siderite in 5 cc. of boiling hydrochloric acid. a. To illustrate the reaction for ferrous iron, take a few drops of the
solution in a clean test-tube, dilute with cold water, and add a little of a freshly prepared solution of potassium ferricyanide, but avoid using a large excess of the reagent, for in this case, owing to the yellow color of the
solution, the precipitate, blue.
b.

when suspended

in

it,

will

appear green instead of

To show

the conversion of ferrous to ferric iron, boil the remainder

of the solution with a few drops of nitric acid, and note the change in color. c. To illustrate the reactions for ferric iron, take a few drops of the solution, oxidized as directed in the foregoing paragraph, dilute with water,

and add a

little

ammonium

sulphocyanate.

potassium ferrocyanide, or test a similar dilute solution with Save the remainder of the solution for the

experiment under 5. The tests with potassium ferricyanide for ferrous iron and with potassium ferrocyanide for ferric iron are exceedingly delicate, and a very good way of applying them is to take drops of each reagent on a clean porcelain plate, and by means of a glass rod or tube to bring in contact with them drops of the solution to be tested.

Detection of Ferrous
especially Silicates.

and Ferric Iron

Most minerals which are insoluble

in Insoluble Minerals, in acids

Lead

KEACTIONS OF THE ELEMENTS.

87

be dissolved after they have been decomposed by fusion with To make the test, take about J ivory spoonful of i^Q finely powdered mineral and three times its volume of powdered bornx-

may

borax.

glass in a rather large closed tube, and fuse in a Bunsen- burner flame. While hot, crack the glass about the fusion by touching

drops of water to

it,

break

off

taining 3 cc. of hydrochloric acid

the end, transfer to a test-tube conand boil for about a minute,

then dilute with 5

parts and
test

cc.

of water.

Divide the solution into two

one for ferrous iron with potassium ferricyanide, the other for ferric iron either with ammonium sulphocyanate or

potassium ferrocyanide. The tests are very decisive, and oxidation resulting from contact with the air and reduction during fusion, which can not be wholly avoided, are so trifling that
be disregarded. Ammonia 5. Precipitation of ferric Iron with Ammonia. added in excess to a solution containing ferric iron precipipractically they

may

tates

the latter completely as

4

Fed, + 3NH OH = Fe(OH)

readily filtered,

+ 3NH C1.
4

brownish-red ferric hydroxide. The precipitate can be

and thus iron can be wholly removed from a solution. Ferrous iron is partially thrown down by ammonia as a dirty green precipitate, which slowly acquires a brown color, owing to the absorption of oxygen from the air.

Lanthanum, La.
The

Trivalent.

Atomic weight,

138.

reactions of this rare earth-metal are given under Cerium.

Lead, Pb.

Bivalent and tetravalent.

Atomic weight,

207.

OCCURRENCE. Lead is very widely distributed in nature and is found most abundantly in galena, PbS. Among various other are cerussite, PbCO -anglesite, combinations, the commonest PbSO pyromorphite, Pb (PbCl)(P0 ) and wulfenite, PbMoO
3
;

4.

It is

worthy DETECTION.

of note that silicates of lead are exceedingly rare.

The formation

of metallic globules

and a coating

of the oxide on charcoal are usually sufficient for the detection of

lead.
1.

Reduction on Charcoal

to

Metallic .Lead
is

and Formation of

a Coating of Lead Oxide.

Lead

readily reduced from its

88

REACTIONS OF THE ELEMENTS.

its

Lead

compounds, and one of the best methods for

detection

is

to

mix

ivory spoonful of the powdered mineral with an equal volume of charcoal-dust and about 3 volumes of sodium carbonate, moisten to a paste with water, transfer to a flat charcoal surface or a shal-

low

cavity,

and heat before the blowpipe

reducing flame.
particles of lead

be made to move about and unite into a which appears bright when covered with the single globule, reducing flame, but on cooling becomes dull, owing to a coating of Lead is, moreover, somewhat volatile, and that portion oxide.

By may

little

in a moderately strong manipulation of the blast, the

vapor unites with the oxygen of the air, and deposits on the charcoal as a coating of oxide, which is sulphuryellow near,, and bluish- white distant from the assay. The coating
off as
is volatile

which passes

when heated

in either the oxidizing or reducing flame.

The lead globule

knife or flattened

and malleable, and may be cut with a by hammering on an anvil.

is soft

The

test

lead globule for use in future experiments. The best idea of the coating of lead oxide may be obtained by removing the globule to a shallow cavity in a fresh piece of charcoal, and heating for a

will be well to

may be made with make a good-sized

cerussite or other lead

compound, and

it

short time before the blowpipe at the tip of the blue cone.

the foregoing reaction on charcoal, the identity of lead is seldom doubtful, but the test is sometimes modified by the presence of other elements, while bismuth gives reactions which
in appearance are very similar to those of lead.
is roasted alone on charcoal at a rather high an abundant white sublimate is formed, resembling temperature, oxide of antimony, and consisting chiefly of some volatile com-

From

When

galena

bination of

PbO and SO

If

roasted carefully, however

(p.

39,

Fig. 41), at a very low temperature,

SO

is

given

off,

and a globule

of lead formed, accompanied

by the yellow coating of lead oxide,

but without much of the white coating just mentioned. In the presence of sulphide of antimony, it is recommended to roast the powdered mineral on charcoal with a very small oxidizing
flame, until the

antimony

is

mostly

volatilized,

and then

to

add

Lead

REACTIONS OF THE ELEMENTS.

89

sodium carbonate to the residue, and heat in the reducing flame so as to form globules of metallic lead, which, however, will still contain some antimony.
a coating of lead oxide on charcoal is moistened with a few drops of hydriodic acid and heated with a
2.

Iodine

Test.

When

small flame, a volatile and very conspicuous chrome-yellow deposit of lead iodide is formed, which appears greenish-yellow when there
is

only a thin coating of it on the coal. A similar coating may be obtained by adding to the powdered mineral from 2 to 4 volumes
of a mixture of potassium iodide

and sulphur (p. 26), and heaton charcoal in a small oxidizing flame, or by heating on a ing gypsum tablet as described on p. 17.
3.

Flame

Coloration.

Lead compounds, when heated

in a re-

ducing flame before the blowpipe,

may impart

a pale azure-blue

color to the flame, showing a greenish tinge in the outer parts. If the experiment is made in the forceps, special care must be

taken not to alloy the platinum.

4.

Solution

and

Precipitation of Lead.

It is best to

use dilute

nitric acid (1 part

HNO

to 2 of water) for the solution of lead

minerals.

Concentrated nitric acid will not answer, owing to the

insolubility of lead nitrate in it. sulphuric and hydrochloric acids

,

From

solutions containing lead,

throw down lead sulphate,

PbSO

4,

and lead chloride, PbCl 2 respectively, as heavy white precipitates. The chloride is quite soluble in hot water and sparingly so in cold, therefore it will not be formed in solutions which are hot or too
dilute.
It is frequently

convenient to dissolve a lead mineral in

rather dilute boiling hydrochloric acid, when, on cooling, most of the lead will crystallize out as lead chloride.
1 in about 3 cc. Tests may be made by dissolving the lead globule from of dilute nitric acid, dividing into 2 parts, and adding to one a few drops of dilute sulphuric and to the other a few dropjs of hydrochloric acid. They

may

also be

made with

the solution obtained by dissolving some lead min-

eral (cerussite or

pyromorphite) in dilute nitric acid.

it

be found advantageous to test for from 3 to 5 ivory spoonfuls of the fine lead as follows: Decompose
In some minerals,

may

90

REACTIONS OF THE ELEMENTS.

in a casserole with nitric acid,

Lithium

powder

add 2

cc.

of concentrated

sulphuric acid, and evaporate until the nitric acid is removed, and white, choking fumes of sulphuric acid commence to come off.

When the
filter off

dish becomes cold, add water, stir for some time, then the insoluble lead sulphate, and test some of it according

tol.
Lithium, Li.
Univalent.

Atomic weight,

7.

OCCURKENCE. This alkali metal is found only in the silicates and phosphates, but is not of very rare occurrence. The commonest
minerals containing
it

are lepidolite,
;

LiK[Al(F.OH)JAl(SiO

)3

spodumene,

LiAl(SiO

3 ),

triphylite,

LiPePO
;

lithiophilite,

XdMnPO

amblygonite, Li[Al(F.OH)]PO 4 tourmaline and mica.

4 ;

and some

varieties of

flame will usually serve for

which lithium imparts to a The test may be made according to directions given on p. 35. The color of a pure lithium flame is nearly monochromatic, showing, when examined with the spectroscope, one bright crimson and one very faint
DETECTION.
color
its detection.

The crimson

yellowish-red band. In testing minerals, it will be found that the appearance of the flame is somewhat modified by the presence of

other substances, especially sodium, which

quantities with lithium, but usually be overcome by the fact that lithium
its
is

is

apt to occur in small

disturbing influence
volatile

may

more

than sodium.

When,

therefore, the assay is first introduced into the flame, the

red of lithium will show before the yellow of sodium, and when the flame is strongest, if the position of the assay is changed to

where the heat

filially

is less intense,

the yellow will disappear

first,

and

the red of lithium will be distinctly seen. Where the proportion of sodium is large, however, the spectroscope must be In testing silicates, it will often be found ad vanresorted to.

tageous to mix the assay with powdered gypsum, and to heat as Colored glasses do directed under potassium (p. 105, 1, <?). much in the analysis of mixed flames containing not assist very
lithium.

Magnesium

REACTIONS OF THE ELEMENTS.

91

The crimson flame of lithium must not be mistaken strontium, which it resembles very closely (p. 116, 1).
Magnesium, Mg. OCCURRENCE.
Bivalent.
is

for that of

Atomic weight,
a very
silicates,

24.
(p. 3),

Magnesium

common element
several of

being found in a great

many

which are
biotite,
a variety

important rock-making minerals; as pyroxene, amphibole,

enstatite,
olivine,

and serpentine.
such

It OCCULTS also in

2 2 magnesite, In the etc. dolomite, MgCa(CO 3 ) a spinel, MgAl 2 O of its compounds, some ferrous iron is isomorphous majority with the magnesium.
;

of

other combinations,
3
;

as brucite,
;

MgO H

MgCO

4 ,

DETECTION. There are no satisfactory blowpipe tests for magnesium, and it is best detected in the wet way by precipitation as

ammonium magnesium
1.

phosphate.

Precipitation as

Ammonium Magnesium PJiospliate. From

strongly alkaline with ammonia, sodium phosphate causes the formation of a white crystalline precipitate of ammonium magnesium phosphate, .6H 2 O. Before 4 MgPO 4

a solution

made

NH

making the test for magnesium, however, it must be ascertained that substances precipitated by ammonia, ammonium sulphide
and ammonium carbonate or
oxalate, have been

removed from

the solution, as otherwise a phosphate of some other element might be thrown down and mistaken for magnesium; while magnesium will not be precipitated by the above-mentioned reagents, provided
(a)

that the solution

is sufficiently dilute, (b)

that

it

contains some

free mineral acid, such as hydrochloric or nitric,

and

(c)

that

it

does not contain an acid with which magnesium forms an insoluble combination (phosphoric, for example). The manner in which the
test is applied

may

be illustrated by the following experiments:

in 3 cc. of hydroa. Dissolve J ivory spoonful of brucite, 2 H, , chloric acid, warm if necessary, dilute with from 5 to 10 cc. of water, add ammonia in excess, and finally a few drops of a solution of sodium

Mg0

phosphate. 1). Dissolve ? ivory spoonful of dolomite,

trace of

CaMg(C0

3) 2

(with probably a
of nitric

FeC0

),

in 3 cc. of boiling hydrochloric acid,

add a drop

92

REACTIONS OF THE ELEMENTS.

Manganese

acid to oxidize the iron, then 5 cc. of water, heat to boiling, add ammonia in excess, and filter, provided a precipitate of ferric hydroxide has formed To the filtrate containing calcium and magnesium chlorides 5). (p. 87,

add ammonium carbonate or 5 and 6), filter, and test the

oxalate,
filtrate

which precipitate calcium with sodium phosphate.

silicates

(p.

60,

For the detection of magnesium in

bodies, see p. 110,
2.

and complex

4.

Alkaline Reaction.

few magnesium minerals become

alkaline after ignition, but the test, which is made by placing the ignited material upon moistened turmeric-paper, is not very decisive nor satisfactory.
3.

Test with Cobalt Nitrate.

Some

of the white or colorless

magnesium compounds, when moistened with cobalt nitrate and ignited before the blowpipe, assume a faint pink color, but the
test is neither

very general in

its

application nor very satisfactory.

Manganese, Mn. In minerals, usually bivalent, but sometimes trivalent and tetravalent. Atomic weight, 55.

OCCURRENCE.

Manganese

is

very widely distributed in na-

ture, small quantities of it, usually a fraction of 1 per cent, being found in many minerals and in most of the silicate rocks. Some of

the
ite,

common manganese minerals are pyrolusite, MnO manganMnO(OH) braunite, Mn O hausmannite, Mn O rhodochro2
;

4 ;

site,

MnCO

3 ;

rhodonite,
4
.

MnSiO,
2 ).

tephroite,

Mn

SiO

and

lithi-

ophilite,

LiMnPO

It

occurs rarely as sulphide (alabandite,

MnS, and

hauerite,

MnS

DETECTION. Manganese can be readily detected by means of the sodium carbonate and borax beads. 1. Test with a Sodium Carbonate Bead, Oxide of manganese dissolves in a sodium carbonate bead, when heated before the
blowpipe in the oxidizing flame, with the formation of sodium The bead thus formed is green when hot manganate, Na2 MnO
4
.

and bluish-green when

cold. The test is a very delicate one, and other substances are not apt to interfere with it. In the reducing flame, the manganese is reduced to MnO and the bead los^s its
color.

Mercury

KEACTIONS OF THE ELEMENTS.

93

The experiment can be made by dissolving a very little pyrolusite, or other mineral containing manganese, in a sodium carbonate bead made
according to directions given on
p. 24.

be made by fusing some of the finely powdered mineral on platinum-foil or in a spoon with sodium carbonate, to which a little potassium nitrate has been added in
similar test

may

order to bring about the oxidation. By this means a very small quantity of oxide of manganese, 0.10 per cent, may be detected by the bluish-green color of the fusion.
borax, giving in the oxidizing flame a bead

Oxide of manganese dissolves in which is opaque while hot, but on cooling becomes transparent and has a fine reddishviolet or amethystine color, due to the presence of a higher oxide
2.

TesticitTi

a Borax Bead.

of manganese. It takes only a very little manganese to give this test, and if too much is added, the color of the bead is so intense

not too strongly colored, it will speedily become transparent while held in the reducing flamo. The manganese is thus reduced to a lower oxide, MnO, and the
that
it

appears black.

If

the bead

is

bead

bead containing MnO is again heated in the oxidizing flame, clouds, which indicate the presence of a higher oxide of manganese, soon make their appearance, and, on Other substances which give cooling, the bead is reddish-violet.
is colorless.

If the

colors to borax
3.

may, of course,

interfere with this test.

of Pliospliorus Bead. This assumes an amethystine color with manganese if heated in the oxidizing flame, but the test is not so delicate nor satisfactory as with borax.
Tlie Salt

The Higher Oxides of Manganese. There are a number of these containing more oxygen than MnO. They dissolve in hydrochloric acid with evolution of chlorine gas, and some of
4.

them, when heated, give oxygen gas (compare Oxygen,

1

p. 100,

and

2).

Mercury, Hg.
rous,

Bivalent in mercuric, and univalent in mercu-

compounds.

Atomic weight,

200.

OCCURRENCE. Mercury is not widely disseminated in nature and is found in only a few minerals, the one which furnishes most

94
/

KEACTIONS OF THE ELEMENTS.

Mercury

of the metal of
all of

rather rare occurrence

commerce being cinnabar, HgS. The following are native mercury amalgam, Ag with
:

Hg

tiemannite,

HgSe

onofrite,

HgSe with HgS

calomel, HgCl,

and the varieties of tetrahedrite containing mercury. DETECTION. The formation of metallic mercury, by heating with sodium carbonate in a closed tube, is usually the most satisfactory test. 1. Closed-tube Tests.
If the

pulverized mineral

is

intimately

dry sodium carbonate, transferred to a closed tube, covered with an additional layer of sodium carbonate about i cm. long, and heated in a Bunsen-burner flame, at
of
first

mixed with about 4 volumes

lic

rather cautiously, the mineral will be decomposed and metalmercury will distil off and condense as globules on the walls of
If

the tube.

mercury is formed, it will appear as a gray sublimate composed of minute globules which may be made to
little

only a

unite

by rubbing with a platinum wire or slip of paper. Mercury compounds, when heated alone in a closed

tube,

usually volatilize without decomposition.

a. To make the test, take about \ ivory spoonful of cinnabar and 2 of dry sodium carbonate, mix them intimately by trituration in an agate mortar, and proceed as directed above. Dry sodium carbonate may be had by heating some of the ordinary material below redness either in a porcelain crucible or on any clean metal surface. The reaction is as follows: HgS 4NaQ C0 3 + + C0 3 + Na a S. On breaking the tube and placing some Ilg of the residue containing Na 2 S on silver along with a drop of water, a test

for the sulphur

b.

may

be obtained

(p.

120,

5).

Heat some cinnabar alone in a closed tube, and observe the black sublimate of HgS. which resembles the- arsenical mirror. Also observe that no metallic mercury is formed.

Open-tube Reaction. A. convenient way of testing sulphide of mercury is to roast a little of the mineral in a rather large open tube, when the products formed are essentially metallic mercury and SO 3 For success in this experiment, the tube is at first heated very hot just above the substance, and then the latter is
2.
.

carefully and gradually so as not to drive off any Often a slight non-metallic black, unoxidized sublimate of HgS. sublimate forms, possibly some combination of oxide of mercury

heated

wry

Molybdenum

REACTIONS OF THE ELEMENTS.

95

and SO but if this is driven up the tube by heat, it is for the most part decomposed, and the resulting gray sublimate will be found to consist of minute globules of mercury, which may be
2 ,

united by rubbing with a wire or slip of paper. If a bit of clean copper is 3. Precipitation upon Copper. placed in a solution containing mercury, the mercury will deposit
in the metallic state

upon the copper, and the

silver-plated.

latter will

then

appear as

if it

had been

Boil a mixture of powdered cinnabar and pyrolusite for a short time with hydrochloric acid, dilute with water, and introduce into the cold solution a copper coin or strip previously cleaned by dipping it into strong nitric The action of the pyrolusite is to liberate acid and washing with water. for the solution of the cinnabar. chlorine (p. 101, 2), which is essential

The

deposition of mercury

the metals.

HgCl,

+ Cu = Hg

upon the copper -j- CuCl 2

.

is

due to a simple interchange of

Molybdenum, Mo.
weight,
96.

Tetravalent

and

sexivalent.

Atomic

OCCURRENCE.
molybdenite,

Molybdenum
2 ,

is

found sparingly in nature, and mostly as

MoS

and wulfenite,

PbMo0

DETECTION. The character of the test for molybdenum depends upon whether the element occurs as sulphide or in an oxidized condition. For the former, an oxidation, and for the latter, a reduction test is recommended. If a fragment of molybdenite is heated on 1. Roasting on Charcoal.
a
flat

charcoal

surface for a considerable

there results, at a short distance

oxide,

Mo0

This

is

time in the oxidizing flame, assay, a coating of molybdic when hot, almost white when cold, and pale yellow

from the

Still nearer to the assay, the charcoal often consists of delicate crystals. is covered with a very thin, tarnished, copper-colored coating of Mo0 2 , which is seen best when cold and by reflected light. The Mo0 3 coating is

touched for an instant with a moderreducing flame, it assumes a beautiful ultramarine- blue color (very characteristic), due probably to a combination of Mo0 2 and MoO.,. the Open Tube. -If thin shavings of molybdenite are 2. Roasting in heated at a high temperature in an open tube, a yellow sublimate of Mo0 3 deposits a little above the assay, and frequently forms a mass of delicate
volatile in the oxidizing flame, and, if

ately hot

crystals.

A fragment of molybdenite, held in the forceps and 3. Flame Test. heated before the blowpipe at the tip of the blue cone, impart,* a pale
yellowish-green color to the flame.

96
4.

KEACTIONS OF THE ELEMENTS.

Reduction Test.
In a test-tube take about
-

Nickel

ivory spoonful of finely

powdered molybdate (wulfenite, PbMoOJ and a scrap of paper not over 1 mm. square, add from 3 to 6 drops of water and an equal quantity of concentrated sulphuric acid and heat until copious fumes of the acid begin to come off, then, after allowing the tube to become cold, add water a drop at a time. The addition of the first few drops of water gives rise to a magnificent deep-blue color, which quickly disappears when the quantity of water added amounts to a few cubic centimeters. The exact nature of this reaction is not well understood, but it is due presumably to a slight reducing action

when only

caused by the presence of the paper. It generally does not succeed well a very minute quantity of mineral is tested.

The salt of phosphorus bead is best. If 5. Reactions with the Fluxes. a small quantity of the oxide is dissolved in the bead in the oxidizing flame, the glass is yellowish-green when hot, changing to almost colorless when In the reducing flame it becomes dirty green when hot, changing to cold. a fine green on cooling. The tests with borax are neither very satisfactory nor decisive.
Nickel, Ni.

Bivalent.

Atomic weight,

59.

OCCURRENCE. Mckel is a comparatively rare element, occurring most often as a sulphide or arsenide, and associated usually with cobalt and iron. Some of its important compounds are

NiAs chloanthite, NiAs gersdorfite, NiS with FeS and genthite, a hydrous silipenthandite, cate of nickel and magnesium. Nickel is found with cobalt in most of the sulphides and arsenides mentioned under the latter element, and much of the metal of commerce is obtained from
millerite,

NiS

niccolite,

NiSAs

5 per cent of

nickeliferous pyrrhotite, essentially FeS, but containing from 1 to isomorphous with the Fe.

DETECTION. The element is usually detected by the color its oxide imparts to the borax bead in the oxidizing flame. 1. Test with a Borax Bead. Oxide of nickel dissolves in the
borax bead, and in the oxidizing flame yields a violet color when hot, not unlike the color given by manganese, but changing to reddish-brown on cooling. By rather long heating in a strong
reducing flame, the bead becomes opaque, owing to the separation of metallic nickel, and if the bead is removed from the wire and
fused on charcoal in the reducing flame together with a granule of

Nickel

REACTIONS OF THE ELEMENTS.

97

metallic tin, an alloy of tin and nickel is formed, and the glass small percentage of finally becomes colorless or nearly so. cobalt will completely obscure the color of nickel, while a trace of

cobalt in the presence of

much nickel may be detected,

as described

on

p. 71,
2.

1.

Test with

a Salt of Phosphorus Bead.

This test for nickel

In the oxidizing flame, with little oxide, is not very satisfactory. the bead is reddish when hot, and becomes pale yellow on cooling,

while with

much

oxide

it

is

brownish-red when hot, becoming

reddish- yellow on cooling. In the reducing flame on platinum wire, the color of the bead is unchanged, but if heated for a long

time on charcoal with a granule of tin, metallic nickel is formed, which alloys with the tin, and the glass becomes colorless.
This reagent, when added to a solution containing nickel, may cause a slight precipitate at first, but the precipitate speedily dissolves and imparts a pale blue color to
3.

Test with

Ammonia.

the solution, which must not be confounded with the

color

much deeper

given by copper when

its

solutions are treated in a similar

way.
when they Occur with Other Special Tests for NicTcel and Cobalt Treat some of the powdered mineral in a casserole with acid Substances. is a sulphide or arsenide), and boil until solu(nitric is best if the mineral
4.

and only about 5 cc. of acid remain. Then dilute with add ammonia in considerable excess, and filter, when the water, boil, nickel and cobalt, or at least the greater part of them, will be found in the Boil the filtrate in a casserole, add caustic potash, filtrate free from iron. and continue the boiling until the ammonia salts are decomposed, and addition of more potash does not produce any additional smell of ammonia. By These this treatment, nickel and cobalt are precipitated as hydroxides.
tion
is

effected

should be collected on a filter and washed once or twice with hot water. Test some of the precipitate with a borax bead in the oxidizing flame, and or present only in very small if it shows the color of nickel, cobalt is absent, If, on the other hand, the bead is blue, 1). quantity (compare p. 71, nickel is possibly present, and may be tested for as
indicating cobalt, follows
:

with the precipitate in a porcelain crucible until the Ignite the paper carbon is burned away, or, if there is a large quantity of the precipitate, some of it may be placed on charcoal and dried out with a blowpipe flame.

98

REACTIONS OF THE ELEMENTS.

dried material
is

Niobium

then ground in a mortar with about twice its volume and a very little fused borax, transferred to a closed tube, and heated gently at first, and finally intensely, before the blowpipe, until the nickel and cobalt, which have now united with the arsenic to form arsenides, fuse into a single globule. The glass is then cracked, and the metallic globule freed as completely as possible from slag. It is next charcoal together with a bit of borax glass, and heated at first placed upon in the reducing flame and then continuously in the oxidizing flame, by which treatment the cobalt is slowly oxidized and imparts to the borax its characteristic color. Sometimes the color is not seen distinctly until some of the fused borax is taken up in the forceps and drawn out into a thread. If the quantity of cobalt is considerable, it may be necessary to remove the globule from the slag (best done by taking the globule in the forceps and plunging it while hot into cold water), and fuse it with a fresh portion of As long as cobalt is present, nickel will not oxidize, and the surface borax.
of metallic arsenic of the bead remains bright while hot, but when the cobalt has all been removed, the nickel commences to oxidize, and its oxide forms a crust over the

The

surface of the bead, which is not as readily dissolved by the borax as the oxide of cobalt. The appearance of the bead, therefore, indicates that
cobalt is no longer present, and if the bead is removed and fused against a fresh portion of borax, it imparts to the latter the brown color characteristic for nickel. Considerable experience in the use of the blowpipe is needed to carry out this operation successfully. Sometimes a mineral may

be fused directly in the reducing flame, to a globule of sulphide or arsenide, and then treated in the oxidizing flame with borax on charcoal as described
above.
If iron is present, it oxidizes before the cobalt.
test,

Copper, which does

not interfere with the

oxidizes only after the nickel has all been retest as

moved. For the detection of small quantities of nickel in pyrrhotite, the given above may be recommended.

Niobium, Nb.
OCCURRENCE.

Pentavalent.

Atomic weight,

94.

Niobium, called also columbium, Cb, is almost invariassociated with tantalum, and together they constitute the acid-formably ing elements of a group of minerals known as the niobates and tantalates.

The two elements are isomorphons with one another, and their compounds are characterized by being unusually heavy. Some of the more common minerals containing them are columbite, tantalite, pyrochlore, microlite,
fergusonite, samarskite, euxenite. and polycrase. occasionally found in silicates, as wohlerite.

Niobium

is,

moreover,

DETECTION.
taining reduction.
it

Niobium

is

best detected

with metallic

tin,

by boiling an acid solution conand obtaining a blue color which is due to

Nitrogen
1.

REACTIONS OF THE ELEMENTS.

99

they must

Reduction Test. As the niobates are usually very insoluble in acids, first be decomposed, which may be accomplished most conven-

iently as follows: Mix the finely powdered mineral with about 5 times its bulk of borax, moisten to a paste with water, take up some of the mixture in a loop on platinum wire, and fuse at a high temperature before the blow-

Make two or three of these beads, remove them from the wire, crush pipe. in a diamond mortar, and boil the powder with 5 cc. of hydrochloric acid,
which should yield a clear or nearly clear solution. On adding some granulated tin, and boiling, the blue color of niobium will appear, which is not
changed to brown by continued boiling, and which rapidly disapupon addition of water. The blue color is due to reduction, but the pears composition of the compound which causes it is not definitely known. If
readily
is present, the violet color due to the reduction of that element appears before the blue of niobium. An acid solution containing niobium, if treated in a similar manner with metallic zinc, becomes sometimes momentarily blue, but the color soon changes to brown, owing to reduction to

titanium

Tungsten gives similar reduction tests, but may be readily distinguished from niobium by a number of reactions mentioned under that
3
.

NbCl

element.
2.

Decomposition

ivith

Potassium Bisulphate.

method that

is

very

generally adopted for the decomposition of niobates and tantalates is to fuse the finely powdered mineral with from 8 to 10 parts of potassium bisulphate. The fusion is ordinarily done in a crucible, but it may also be made

which is required need not exceed faint redness and the glass is not attacked. When the decomposition is complete, as shown by the disappearance of dark particles, the tube may be inclined and
in a test-tube, since the heat

turned while cooling, causing the fusion to solidify as a thin crust on sides, so that it may be more readily dissolved on subsequent treatment.
is

its

It

digested with cold water, which requires considerable time (the application of heat is not recommended), and there is left an insoluble white residue consisting of niobic and tantalic oxides, while the bases are in solution.

The insoluble oxides are collected on a filter and washed, and if a portion of them is treated in a test-tube with hot concentrated hydrochloric acid, and
boiled with granulated tin, the blue color due to niobium may be obtained. For the separation of small quantities of tungsten and tin from the in3. soluble niobic and tantalic oxides, see p. 126,
3.

Oxide of niobium gives no satisfactory reactions with the

fluxes.

Nitrogen, N.

Trivalent and pentavalent.

Atomic weight,

14.

OCCURRENCE. Nitrogen is the characteristic non-metallic element of nitric acid, HNO and of the nitrates. The simple nitrates of the metals are soluble in water, and are not found as
3
,

100

BEACTIONS OF THE ELEMENTS.

is

Oxygen

minerals in regions where there

regions, however, they
cial importance, as the

a considerable rainfall.

In arid

may

accumulate and be of great commer-

sodium nitrate deposits of Chili and Peru. The ammonium compounds also contain nitrogen, and have already been mentioned on p. 43.

DETECTION OF NITRATES.
better, in a

When

heated in a closed tube,

or,

bulb tube, with potassium bisulphate, nitrates are decomposed and yield NO 3 gas, which may be detected by its red color (seen best by looking into the tube lengthwise), and also by
its odor.

Potassium bisulphate
off

may be

omitted in testing nitrates

of the

heavy
given

metals, for they are so readily

decomposed that

NO

gas

is

even on moderate ignition.

See the platinum metals,
Bivalent.
p. 104.

Osmium,

Os.

Oxygen, O.

Atomic weight,
is

16.

OCCURRENCE.
crust of the ea^rth

Oxygen

the most abundant element in the

With the exception of the native ele(p. 3). the sulphides, fluorides, and hajogen salts, oxygen is ments, Many elements unite with oxygen in present in all minerals.
varying proportions; those containing the smallest quantity of oxygen are called lower oxides, or ous compounds (FeO ~ ferrous
oxide),

and those with more oxygen, higher oxides, or

2
s

ic

com-

Usually no direct test is made for oxygen, but if determined to be a salt of some oxygen acid, as carbonic or silicic, which may be readily done, it must contain oxygen while, on the other hand, if it is a sulphide or chloride, it probably

pounds (Fe DETECTION.

a mineral
is

= ferric oxide).

will not contain oxygen.

However, oxy sulphides, oxy chlorides,

and oxyfluorides, although rare, are known, as are also chlorides and fluorides containing water of crystallization. For some of the
higher oxides, the closed-tube
test,

or the liberation of chlorine

when
1.

dissolved in hydrochloric acid, may be applied. Closed-tube Reaction. Some of the higher oxides,
is

when
and

heated in a closed tube, yield oxygen gas, which

colorless

Phosphorus

REACTIONS OF THE ELEMENTS.

101

odorless,

but

may

be detected by burning a piece of charcoal

in the tube.
Place some fragments of pyrolusite, Mn0 2 , in the bottom of a closed tube, and a little above, a sliver of charcoal (compare Fig. 45, p. 62) ; then heat the charcoal alone, and observe that although it gets red hot, it does

not burn, owing to the limited supply of air in the tube. Keeping the charcoal hot, apply heat to the pyrolusite, and as soon' as oxygen com-

mences

to be given off, the charcoal will

burn brightly, and continue to do

so as long as

oxygen

is

supplied by the mineral.

The

reaction

is

3Mn0 =
2

Mn

20.

2.

Liberation of Chlorine.

When

some

of the higher oxides

is liberated,

are dissolved in hydrochloric acid, chlorine gas

which

may be recognized by its peculiar odor and bleaching action, while ordinary oxides when similarly treated do not set chlorine free. These differences are illustrated by the following equations:

Mn0 +
2

4HC1
6HC1
is

Fe O
2

= MnCl + 2H O + = 2FeCl + 3H O.
a

201.

Whether
acid unite to

chlorine

ter of the metal.

upon the characThe oxygen of the oxide and hydrogen of the form water, and if the chlorine thus available is more

liberated or not depends

than

sufficient to satisfy the valence of the metal, the excess will

be liberated.
Treat one ivory spoonful of finely powdered pyrolusite, Mn0 2 , in a testtube with 5 cc. of hot hydrochloric acid. Observe the odor of the escaping gas, and also bleach a piece of moistened litmus-paper by holding it for a
short time within the test-tube.

Palladium, Pd.

See the platinum metals,

p. 104.

Phosphorus, P.

Pentavalent (usually).

Atomic weight,

31.

OCCURRENCE.

Phosphorus
3

is

the characteristic non-metallic

4 ,

and its salts, the phosphates. element of phosphoric acid, Although a great many phosphates are known, the majority of them are rare minerals, and many of them are isomorphous with
arsenates and vanadates.

H PO

The following will serve

as illustrations

102
apatite,

REACTIONS OF THE ELEMENTS.

Phosphorus

Ca (CaF)(PO
4

4 ),

triphylite,

Li(Fe,Mn)PO

and

vivianite,

Fe (P0
3

4)2

.8H 0.
2

DETECTION. Ammonium molybdate is the best reagent for the detection of phosphates, but the flame coloration or the reduction test with magnesium may be used.
1.

Test

with

Ammonium

Molybdate.

When

nitric

acid

solution of a phosphate is added to a solution of ammonium molybdate, according to the directions given beyond, a yellow
precipitate
10
4

of
34

ammonium
.l^H 0,
2

pliospTiomolybdate,

Mo (NH P0
)2

is

thrown

down,

and

approximately furnishes an

Only a little of the phosphate soluexceedingly delicate test. tion should be added to the ammonium molybdate at first, since
the precipitate
present.
slightly

may

not form

if

an excess of phosphoric acid

is

The precipitation should take place

in a cold or only

warmed

solution, for if heated to boiling, other things,

especially a corresponding arsenic compound might be throAvn down and mistaken for the phosphate precipitate. If the mineral
is

insoluble in nitric acid,

it

may

be

first

fused in a sodium

carbonate bead and then dissolved in this acid.

An

acid other

case

may be used for dissolving the mineral, but in that best to nearly neutralize the excess of free acid with ammonia, before adding the solution to the ammonium molybdate. When applying this test, it is recommended to follow quite
than
nitric
it is

closely the details of the experiment as given below.

Dissolve i ivory spoonful of apatite in about 3 co. of warm nitric acid, and pour a few drops of the solution into another test-tube containing about 5 cc. of ammonium molybdate, when, after standing a few minutes
in the cold, the yellow precipitate will

make

its

appearance.

phosphates when heated before the blowpipe impart a pale bluish-green color to the flame, while others often show the reaction if moistened with concentrated
2.

Flame

Test.

Many

The color, although not very sulphuric acid and then heated. marked, is often sufficient for the identification of a phosphate
(compare
p. 136).

Platinum

REACTIONS OF THE ELEMENTS.

103
.

of wavellite, A1 6 P 4 19 or apatite. In case the latter mineral is used, it is necessary to 2 0, moisten the fragment with sulphuric acid, and then the color is distinct for

The experiment may be made with fragments

12H

only a short time.

Reduction with Metallic Magnesium. Phosphates of the alkalies and alkaline earths, when strongly ignited in a closed tube with magnesium, are reduced, with the formation of a
3.

phosphide.

This,

when moistened with

able odor of phosphuretted hydrogen,

garlic odor of arsenic.

water, gives the disagreesomewhat like the 3

PH

When

phosphates of aluminium and the

is

heavy metals are to be

tested, it

best to fuse the powdered

mineral with 2 parts of sodium carbonate on charcoal, to remove and grind up the fused mass, and then to ignite the powder with

magnesium.
The experiment may be made with apatite or wavellite. In the latter case, however, the mineral should first be fused with sodium carbonate.
Take a piece of magnesium ribbon about 25 mm. long, roll or fold it up Next add the into a compact mass, and drop it into a closed glass tube. finely powdered phosphate, tap the tube so as to bring the powder as much
as possible in contact with the magnesium, and ignite very strongly with a blowpipe flame, being careful to hold the tube in such a manner that, if an

explosion should occur, the contents would not be shot out into the face. Crack off the end of the tube by dropping water upon it while it is still
hot, moisten the contents with a few drops of water, and observe the odor of the phosphuretted hydrogen; or, after allowing the tube to become cold, introduce a drop or two of water, and observe the odor at the end of the

tube.

Platinum, Pt.

Bivalent and tetravalent.

Atomic weight,
it

195.

OCCURRENCE. Platinum is found native, but some iron and traces of other metals belonging
a
.

then always contains

to the

platinum group.

The only mineral containing platinum in chemical combination is sperrylite, PtAs DETECTION. The color, high specific gravity, infusibility, and insoluacid, are properties which serve for the identification of the metal occurs in sand, it may be concentrated by platinum. For a more washing as described under gold, but without using mercury. definite test for platinum, it is recommended to fuse the metal in a cavity
bility in

any single

When

on charcoal with some

test-lead,

using borax,

if

necessary, to take

up

104

REACTIONS OF THE ELEMENTS.

Platinum

The metallic globule, freed from slag by hammering, is then impurities. treated with dilute nitric acid (1HN0 3 2H a O), which dissolves everything but the platinum metals and gold, and these are then collected upon a
:

The finely divided platinum thus washed, and ignited. obtained dissolves readily in aqua regia, giving a reddish-yellow solution Pt01 6 , which should be evaporated containing hydrochlorplatinic acid, 2
filter-paper,

nearly to dryness, at a moderate heat, treated with hydrochloric acid, and again evaporated. It should be finally taken up with a little water, filtered
necessary, and added to a concentrated solution of ammonium chloride, a yellow precipitate of ammonium platiuic chloride, (NH 4 ) 2 PtCl 6> The precipitate, if collected upon a filter, washed will be thrown down.
if

when

some other metals of the platinum group.

filtrate.

with alcohol, and ignited, yields a gray platinum sponge, containing often Gold, if present, will be in the

The Rarer Metals of the Platinum Group.

Ruthenium, Ru. Atomic weight, 101.5. Rhodium, Kh. Atomic weight, 103.

Atomic weight, 106.5. Atomic weight, 190.8. Osmium, Os. Iridium, Ir. Atomic weight, 193.1.'
Palladium, Pd.

OCCURRENCE. All the above metals are found in small quantity in Iridium and palladium, containing some platinum and native platinum. traces of the other platinum metals, are found native. Iridosmine is a mixture consisting chiefly of iridium and osmium. Laurite is essentially RuS 2 . DETECTION. The analysis of the platinum metals is one of the difficult problems of analytical chemistry for which advanced works on the subject

should be consulted.

A few

has an and disagreeable odor, somewhat resembling broBxceedingly penetrating mine. The vapors are poisonous and should not be breathed too freely.
is

Osmium

characterized

special tests, however, will be given. by a volatile oxide, Os0 4 , which

The odor may be obtained by heating the powdered mineral in an open tube, and a very characteristic test may be made by bringing the upper end
into the latter, which will
of the tube within a Bunsen-burner flame, so that the osmic oxide will pass become luminous, owing to the reduction of the

osmic oxide and to the glowing of the finely divided metallic osmium. The odor of osmium is also obtained when the finely divided mineral is oxidized by fusing in a bulb tube with sodium or potassium nitrate. Iridium and iridosmine are characterized by their hardness (6-7) and Iridium is insolubility in acids, even aqua regia failing to dissolve them. oxidized by fusion with sodium nitrate (this may be done in a partially

Potassium

REACTIONS OF THE ELEMENTS.

105

bulb tube), and the fused mass when boiled with aqua regia yields a deep
red to reddish-black solution.

Native palladium exhibits a bluish tarnish, which is lost by heating in the reducing flame, the color becoming like that of platinum, but is regained by heating moderately in the air (best in an open tube). When a piece is flattened on an anvil to expose a maximum surface, and fused with potassium bisulphate, the metal is oxidized and dissolved to some extent. On soaking out the fusion in water, and adding a very small crystal of potassium iodide, a black precipitate of palladous iodide is formed, which dissolves in a large excess of potassium iodide, giving a deep wine-red color.

Potassium, K.

Univalent.

Atomic weight,
is

39.1.

OCCURRENCE.
although
is

Potassium

its

simple

salts are

a very abundant element, and, soluble in water, it occurs in

silicates.

insoluble combinations in

many

Orthoclase,

KAlSi

8 ,

one of the most abundant minerals in the crust of the earth.

The most important minerals for the production of potassium compounds are certain soluble chlorides (sylvite, carnalite), which
are found in connection with deposits of rock
salt.

DETECTION.

means

of

Flame coloration furnishes the most convenient testing for potassium, and, where this test cannot be
as

applied,

precipitation
to.

potassium

platinic

chloride

may

be

resorted
.

I.

Flame

Test.

Volatile potassium

pale violet, and the test stance, held in the forceps or in a loop on platinum wire, into the hottest part of the Bunsen-burner or blowpipe flame. The flame

compounds color the flame may be made by introducing the sub-

not very strong and is easily obscured by other elements, especially sodium, but by viewing it through blue glass of sufficolor
is

may be absorbed, and the flame will be distinctly seen of a violet or purplish-red potash color, depending upon the depth of color of the glass.
cient thickness, the disturbing colors
.

Take up some
it

sylvite,

KC], in a small loop on platinum

wire, intro-

duce

into a Buusen-burner flame, and observe the color. the flame through various thicknesses of blue glass.
I.

Also examine

Add

little

sodium chloride

to the potassium chloride,

and repeat the

foregoing experiment. c. In testing silicates from which, under ordinary conditions, the potas-

106

REACTIONS OF THE ELEMENTS.

is

Potassium

slum

useful:

Mix the

not readily volatilized, the following method will be found very finely powdered mineral with an equal volume of powdered

gypsum, and having heated a platinum wire until it gives no color to the flame, touch the end of it to a drop of water and then to the mixture, so as

up a little of the latter. Introduce this carefully into the hottest part of a Bunsen-burner flame, and observe the color, making use of blue glass to absorb the yellow resulting from sodium, which is almost sure to be present, in traces at least, with potassium. Gypsum, when fused with the
to take
it volatilizes,

mineral, forms calcium silicate and potassium sulphate, and the latter, when imparts the color to the flame. Instead of a straight wire, a

small loop may be used for taking up the mixture, but it is necessary to have a heat sufficiently intense to fuse the minerals together and liberate the potassium sulphate. The test is quite delicate.

the exception of the silicates, phosphates, borates, and salts of a few rare acids, the potassium compounds become alkaline upon intense ignition before the
2.

Alkaline Reaction.

With

blowpipe. The test is not so satisfactory as that minerals containing other alkalies and alkaline earths.
3.

made with

Precipitation as Potassium Platinic Chloride. If hydrois added to a rather concentrated, 2 PtCl 6 chlorplatinic acid,

neutral, or slightly acid solution containing potassium, a yellow crystalline precipitate of potassium platinic chloride, K Q PtCl 6
,

will be formed,

which furnishes an excellent means

for detecting-

The precipitate is sparingly soluble in water, and potassium. Ammonium compounds almost absolutely insoluble in alcohol.
yield a similar precipitate,
a.

(NH PtCl
4

)2

6.

of water,
Z>.

test, dissolve a little sylvite, KC1, in a few drops and then add a few drops of hydrochlorplatinic acid. To adapt the test to insoluble silicates, proceed as follows: Fuse the powdered mineral with sodium carbonate, as described in detail under

In order to make the

silicates (p. 110,

4).

Pulverize the fused mass, treat

it

in a test-tube with

and after cooling add about Next add an equal volume of alcohol, filter through 2 cc. of water and boil. a small paper, and add a few drops of the hydrochlorplatinic acid solution
little

hydrochloric acid, evaporate to dryness,

to the filtrate in order to precipitate the potassium.

See the rare metals of the platinum group, p. 104. Rubidium, Kb. Univalent. Atomic weight, 85.5. OCCURRENCE. This rare alkali metal is found very sparingly together with caesium in some varieties of lepidolite.

Rhodium, Rh.

Silicon

REACTIONS OF THE ELEMENTS.

107

DETECTION.
is

Rubidium

is

insoluble platinic chloride,

Rb PtCl 6
2

very similar to potassium, and forms an Examination with a spectroscope

.

needed for

its

identification.

Selenium, Se.

Bivalent and sexivalent.

Atomic weight,

79.

OCCURRENCE. This rare element is found usually in combination with the metals, as selenides; clausthalite, PbSe; tiemannite, HgSe, etc., which
are analogous to sulphides. DETECTION. When a substance containing selenium is heated before the blowpipe on charcoal, a curious odor may be observed which is de-

scribed by Berzelius as similar to that of radishes and also of decaying It is impossible to describe this odor, but only a few trials are radishes. to render it familiar, and it is so pronounced and characteristic necessary

that a very minute quantity of selenium may be detected by means of it.. If the selenium is present in considerable quantity, it volatilizes as a brownish smoke, and some of it deposits at a little distance from the assay as a
silvery coating of oxide, Se0 2 , which may have an outer border of red, owing to admixture of finely divided selenium. If the coating is touched with the reducing flame, the selenium volatilizes, and imparts a magnificent

azure-blue color to the flame.

istic test.

This

is

an extremely delicate and character-

In the open tube, selenium yields a white oxide, Se0 2 , which usually crystallizes in radiating prisms on the sides of the glass, and is reddened by an admixture of finely divided selenium. The sublimate is volatile, and,
if

tube

driven up the tube, it may be made to give a beautiful blue color if the is held so that the vapors at the end pass into the reducing part of a

Bunsen-burner flame. In the closed tube, selenium volatilizes from some of its compounds, and condenses as black globules fused against the glass, but where the globules are very minute, they transmit some light and cause the thinnest Owing to the air in the part of the sublimate to appear red or brown. tube, a little oxide, Se0 2 may form, which crystallizes on the glass above
,

the selenium.

Silicon, Si.

Tetravalent.

Atomic weight,

28.

most abundant which constitute the crust of the earth element in the minerals
to oxygen, silicon is the

OCCURRENCE.

Next

In combination with oxygen, it forms the very common mineral, quartz, SiO 2 and it is the characteristic non-metallic
(p. 3).
,

element in the

silicates,

or salts of silicic acid.

Silicates are very

numerous, and

salts of several kinds or types of silicic acids are the most important of which are as follows: recognized,

108

REACTIONS OF THE ELEMENTS.

Orthosilicic acid,

Silicon

Metasilicic acid,
Trisilicic acid,

Tetrasilicic acid,

H SiO H Si O = 2H SiO,. H Si O H Si O = 2H Si O
4 4
.

B.

10

5.

acids, written as above in a progressive series, differ from one another by addition of SiO 2 There are no methods for deter.

The

any given except quantitative chemical analyses from which the ratio between the silica and the metals may be calculated (p. 6).
silicate

mining just

what kind

of silicic acid is contained in

For example, in

forsterite,

lent, the formula must be

Mg Si = 2 1, and, Mg being bivaMg SiO a salt of orthosilicic acid. In

:

4 ,

orthoclase, 3, and potassium being univalent and aluminium trivalent, the formula is KAlSi O In the majorof cases, the empirical formulae of the silicates have been ity determined with a fair degree of accuracy, and most of them have been found to correspond to the few types of acids already mentioned, the orthosilicates and metasilicates being the commonest, 'i'he formulae of some silicates, however, and among them a few
:
:

Al

Si

8.

The true constitution of the silicates, that is, their structural formulae or the manner in which the atoms are united to one another, is uncertain, and largely a
of the
ones, are uncertain.

common

matter of conjecture.
potassium,
calcium,

It

has been found that the metals sodium,

ferric
iron,

magnesium, ferrous and

and

aluminium, are of very common occurrence in the silicates, and that orthosilicates are more soluble in acids than metasilicates

and

polysilicates.

DETECTION.
silica

The surest method

for the identification of a

mineral in solution in an acid, and obtain The residue or skeleton of gelatinous by evaporation. silica obtained in the salt of phosphorus bead furnishes a simple
silicate is to get the

but not very delicate test. 1. Formation of a Jelly.

acid the solution

When

a silicate

is

dissolved in
silicic acid,

may

be regarded as containing free

when

4 possibly and, upon evaporation, the latter can no longer remain in solution, but yields a
4
,

H SiO

there comes a point

Silicon

REACTIONS OF THE ELEMENTS.

If the

109

evaporation is continued until the mass becomes dry, and the latter is then moistened with strong acid and digested with water, the bases will go into solution, while
gelatinous mass.

the silica remains insoluble and

may

be separated by

filtering.

Comparative tests have shown that gelatinization is more readily obtained with nitric than with hydrochloric acid, although in many cases either will answer. As most silicates are insoluble
in acids, a previous decomposition,
ate, is usually necessary before

by fusion with sodium carbon4).

applying the test (compare

To

illustrate the foregoing, in the case of soluble silicates, take

,

about 2

ivory spoonfuls of finely powdered calamine (ZnOH) a Si0 3 or nepheline, essentially ]S"aAlSi0 4 mix in a test-tube with about 1 cc. of water, then
,

add

3 cc. of nitric or hydrochloric acid,

warm, and observe that the mineral

Boil the solution, and it will soon become yields a perfectly clear solution. thick from the separation of gelatinous silica. The gelatinous silica is insoluble in water and acids, and, if thoroughly washed with water and
dried over sulphuric acid, has essentially the composition Si0 3 2 reason for adding the water at the beginning of this experiment
.

The
is

to

thoroughly mix the mineral with the

acid.

If omitted, the acid

when

it first

comes
silica

in contact with the dry material will often form a layer of gelatinous over the powder and prevent a portion of it from going into solution.

2.

cates are completely

Separation of Silica without Gelatinization. Some silidecomposed by boiling with acids, the bases

going into solution, while the silica is left in an insoluble condiFrom the appearance tion, but without any formation of a jelly.
of the test
lias
it is

sometimes rather

difficult to tell

whether a mineral

been decomposed or not, but the separated silica, having a low index of refraction, makes the liquid in which it is suspended

appear translucent and almost clear, while the fine, suspended powder of an insoluble mineral causes the liquid to appear white

and evaporate a drop of the solution on a piece of glass or platinum, when, if a considerable residue is left, it indicates that a decomposition has taken place,

and milky.

sure test

is

to

filter,

and the bases have gone into

solution.

experiment to illustrate the above may be made by boiling 2 ivory spoonfuls of finely powdered serpentine or stilbite with 5 cc. of hydrochloric

An

acid.

REACTIONS OF THE ELEMENTS.

3.

Silicon

Fusion with Sodium Carbonate. When quartz, SiO or a silicate is fused with sodium carbonate, a sodium silicate is formed. the fused mass will be soluble in acids, and, upon Moreover, evapo2 ,

ration of

the solution, gelatinous

silica

separates,

as in

1.

Fusion with sodium carbonate is indispensable for the solution and subsequent analysis of insoluble silicates (compare 4).

To

illustrate the foregoing

,

quartz, Si0 2

and an equal volume

paragraph, take some very finely powdered of sodium carbonate (rather less sodium

carbonate than more), make into a paste with water, then support some of the mixture on a small loop on platinum wire and heat with an intense
Instead of fusing on a platinum loop, the experiment succeeds beautifully when a minute quantity of the mixture is heated intensely on a clean charcoal surface. If successful, a transparent bead should result,

blowpipe flame.

and the experiment illustrates the process of glass-making. The sodium carbonate brings about a decomposition of the quartz, the anhydride of silicic acid, with the formation of sodium silicate and evolution of carbon dioxide gas, the reaction Joeing somewhat as follows: 2Na a CO, -f- Si0 2
.

JSTa 4 Si0 4

+2C0

9.

Special Treatment for the Detection of the Common Elements in Silicates. The methods to be described are for the detec4.

tion of aluminium, iron, calcium,

commonly

present in silicates, but to devise a

and magnesium, which are very scheme applicable to

would require the elaborate methods of qualitawhich are beyond the scope of the present work The scheme has been made as simple as possible, and the tests can be performed upon a small quantity of material and in a
all possible cases

tive chemical analysis,

short time, but the beginner will find

details quite closely.
If

it

necessary to follow the

a silicate

is

insoluble in acids,

it

may

be decomposed readily

by fusion with sodium carbonate and then dissolved. For a test, mix a scant ivory spoonful of the finely powdered silicate with 3 parts of sodium carbonate, make into a paste with a drop of water and then take up a portion of the material on a loop on platinum wire and fuse before the blowpipe. Make two or three beads, if
necessary, rather than attempt to fuse all of the material at once. In almost all cases there results after fusion an opaque mass, the presence of various oxides contained in the mineral, mixed with

Silicon

REACTIONS OF THE ELEMENTS.

Ill

the sodium silicate and excess of sodium carbonate, preventing the formation of a clear glass as in 3. The several beads, after

removal from the platinum wire, are pulverized in a diamond mortar, transferred to a test-tube, treated with about 1 cc. of water

and evaporated to dryness, being careful toward the end of the operation not to allow the tube to become very hot. After cooling, moisten the contents of the tube with about 3 cc. of hydrochloric acid, boil for a few seconds,
of nitric acid,

and an equal volume

then add 5
silica

so as to decompose any basic salts formed during the evaporation^ cc. of water, heat to boiling, and remove the insoluble

by filtering. white, and may be

The

silica

tested as follows

separated at this point should be Wash well on the paper with

:

water, but do not add the washings to the first filtrate, puncture the paper, and, by means of a jet of water, wash the silica into a clean test-tube, then add a little potassium hydroxide and boil,

when- the

The

pure, will go wholly into solution. filtrate from the silica contains the bases, with the iron in
silica, if

the ferric condition, owing to the use of nitric acid. The solution is heated to boiling, and ammonia is added in slight excess to precipitate

aluminium and ferric hydroxides (p. 42, 2, and p. 87 5), which are collected on a filter and washed with water. If the pre-

cipitate is light-colored, iron is absent, or present only in small

quantity if it is reddish-brown, indicating iron, aluminium be also present, and must be specially tested for, as follows
;

may By

means
filter,

of a knife-blade or spatula scrape off the precipitate

from the

and with the aid of a

jet of

watei transfer

it

to a clean test-

up the paper with the precipitate, and drop it inta Have about 5 cc. of water present, then add some potassium hydroxide (a piece of stick potash 5 mm. long), and boil, by which treatment aluminium hydroxide is dissolved, and may be separated from the iron by filtering. The solution is made acid with hydrochloric acid, boiled, and ammonia added in excess, when aluminium, if present, will be precipitated. Whether ferrous or ferric iron is contained in the mineral must be determined
tube, or fold

the test-tube.

by

special tests (p. 85,

4).

The

filtrate

from the iron and aluminium may contain calcium

112

REACTIONS OF THE ELEMENTS.

(if

Silicon

much magnesium is present, some of it may have been precipitated by ammonia along with the iron and alumin ium). It is heated to boiling, and a little ammonium oxalate
and magnesium
added in order
oxalate
liable to
is

to precipitate the calcium (p. 60,

6).

Calcium

run through

precipitated in a very finely divided condition, and is It is best, therefore, to let the filter-paper.

precipitate stand for about ten minutes before filtering, and then, if the filtrate is turbid, to pass it a second or third time through

the same

filter

until the pores of the paper

clear filtrate is obtained.

is

become stopped, and * To the filtrate, a little ammonium oxalate

added to make sure of the complete precipitation of the calcium, and, if no precipitate forms, some sodium phosphate and strong ammonia are added to precipitate the magnesium (p. 91, 1). If a precipitate does not form immediately, however,
considered that magnesium
is .present,
is
it

must not be

absent,

for, if
is

and especially

if

the solution

only a small quantity warm, the precipitate

may

not appear until after standing some time in the cold. For alkalies, the tests given under sodium (p. 116, 1, c) and potassium
(p. 105,
5.
1, c)

are recommended.

Oxide of silicon Test with the Salt of Phosphorus Bead. dissolves with difficulty in a salt of phosphorus bead therefore,
;

fused in the bead, the silica, SiO 2 when some powdered is left as an insoluble skeleton or translucent mass, while the bases
silicate is
,

go into

solution.

The

test

may be recommended on

account of

its

simplicity, but

it is

not delicate.

In order to test the above, touch the phosphorus bead when hot to any powdered silicate, so as to take up a quantity which before heating does not quite cover one half the surface of the bead, and then heat before the

As the bases dissolve in the hot blowpipe, in the hottest part of the flame. when examined glass, the silica moves about and collects together, and,
with a lens, it appears as a translucent mass, usually occupying a position in about the center of the bead, and is quite different in appearance from

any undissolved mineral. mineral in the bead, and

mineral.

better to heat a fragment of the some time, the translucent silica skeleton may be seen surrounding a particle of the still undecomposed
it is

Sometimes

after igniting for

Silicates are quite soluble in 6. Decomposition with Borax. a borax bead, and it may be sometimes found convenient to sub-

Silver

REACTIONS OF THE ELEMENTS,

113

stitute this treatment for fusion

with sodium carbonate in order

to

decompose a
Silver,

silicate.

Ag.

Univalent.

Atomic weight,

108.

OCCURRENCE.

Some

silver is

found native and as chloride or

bromide, but by far the greater part of the metal of commerce is obtained from its compounds with sulphur. A few of the most

important silver minerals are argentite, pyrargyrite, 3Ag2 S.Sb 2 S proustite,

3
;

Ag S
2

stromeyerite,
a a
;

AgCuS;

5Ag

S.
;

Sb,S

polybasite,

essentially

3Ag S.As S, 9Ag S.Sb S

2 2
3

stephanite,
cerargyrite,

AgCl and embolite, AgCl with AgBr. Silver is found in several combinations with tellurium, and in small quantity in many as in galena, sphalerite, chalcocite, bornite, and tetrasulphides hedrite, which are then called argentiferous. Owing to the value of silver, it is profitable to extract it from ores which con;

tain only a small percentage of the metal.

An ore, for example, one per cent of silver would yield 291 troy ounces of the having metal per ton, and, under favorable conditions, ores containing
than one tenth of the above amount

less

may

DETECTION.

The metal

is

usually detected

be profitably worked. by reduction to

the metallic state or by precipitation as silver chloride. From pure silver minerals, 1. Reduction to Metallic Silver. the metal may be readily obtained on charcoal by fusion before
the blowpipe with about 3 volumes of sodium carbonate. The metal easily fuses to a globule, and this is bright both while in

the flame and after cooling, for the metal does not tend to oxidize.

The

silver globule is malleable,

can be flattened by hammering on

an anvil, and may be further tested according to 3. When other readily reducible metals are present, the globule obtained by the above treatment will not be pure silver, and fusion with test-lead

and cupellation on bone-ash

rax
is sufficient

2)

may

then be resorted

to.

Often

fusion on a clean charcoal surface in the oxidizing flame with boto free the metal

substances oxidize,
of pure silver.

from impurities, since the foreign dissolve in the borax, and leave finally a globule
combination with only volatile elements

When in

114

REACTIONS OF THE ELEMENTS.

Silver

(sulphur, arsenic, antimony), a silver globule may be obtained by heating some of the mineral alone on charcoal in the oxidizing
flame.
it

Silver is volatile to a slight degree, but alone

on charcoal

gives no characteristic coating. When silver is associated with lead and antimony, however, the coatings which these latter elements give on charcoal assume a reddish to deep lilac tint, which
serves as a very certain indication of the presence of silver.
of Small Quantities of for the detection of even very small quantities of silver in minerals or ores is to mix an ivory spoonful of the finely pow2.

Cupellation

on Bone-ash and Detection

Silver.

method well adapted

dered material with an equal volume each of borax glass and test-lead, transfer to a rather deep, funnel-shaped cavity in a compact piece of charcoal, and fuse before the blowpipe for some time in a reducing flame until
the lead, which takes up all the silver, has united into one globule, while the impurities dissolve in the borax. Later an oxidizing flame may be used in order to form lead oxide, which dissolves in the borax and assists in taking

up

the impurities. After cooling, the lead is removed from the charcoal, and freed from adhering slag by hammering on an anvil. cupel is next prea cavity on charcoal with bone-ash, and pressing the latter pared by filling

down firmly by means of an agate pestle or other smooth rounded surface, such as the back of the metal scoop (Fig. 22), so as to form a shallow deLoose particles of bone-ash are removed pression about 15 mm. in. diameter. by inverting and gently tapping the charcoal, and the cupel is heated inThe lead button is tensely before the blowpipe in order to expel moisture. then placed carefully upon the cupel, so as not to disturb the surface of the bone-ash, and fused before the blowpipe, first in the reducing flame until a bright metallic surface is obtained, and then in a small oxidizing flame It is necessary to heat in the oxidizing flame for several minutes (Fig. 41). in order to oxidize the lead, during which time the surface of the button shows a play of rainbow colors, due to a thin film of lead oxide, which conFinally, when stantly flows to the sides, and is absorbed by the bone-ash. the last of the lead is oxidized, the play of color ceases, the globule is said to " bliclc" and the operation is completed. Frequently the amount of lead oxide formed is so great that it cannot all be absorbed by one cupel. The button then becomes surrounded by, and seems to float upon, the fused lead oxide, and when this happens, it is best to interrupt the operation and oxidize the last of the lead upon a fresh cupel. Considerable practice is needed in order to make the silver assay easily and quickly, but when the necessary skill has been acquired, the operation may be performed in less than fifteen minutes, and by assaying samples of known value and saving the silver beads for comparison, one can soon learn

Sodium

REACTIONS OF THE ELEMENTS.

115

to judge of the relative values of ores. By starting with weighed quantities of material, and especially by making use of the special apparatus men. tioned in Plattner's elaborate treatise,* very good quantitative determinations of silver may be made by means of the

blowpipe assay.

3.

Precipitation as Silver Chloride.

Silver chloride, AgCl, is

very insoluble in water and dilute nitric acid. of silver chloride will therefore form if silver
lute nitric acid
:

A white precipitate
is

dissolved in di-

(1HNO, 2H O) and a few drops of hydrochloric acid

2

are added to the solution.

quantity of the precipitiate is appears as a turbidity, while if ic is considerable it collects as a curdy mass. It darkens on exposure to light and is soluble in ammonia. A globule of silver from one of the readily
small
it

If the

foregoing experiments may be tested in this way. It is also often convenient to test for silver by dissolving a mineral in hot, concen-

and filtering if necessary, to the silver with hydrochloric acid. The precipitate, if precipitate collected on a filter, may be tested according to 1.
trated, nitric acid, and, after dilution,

Sodium, Na.
OCCUIIRENCE.

Univalent.

Atomic weight,
is

23.

a very abundant element, and although its simple salts are all soluble in water and are not ordinarily found as minerals in wet regions, they often accumulate in
desert or dry places, and form deposits of great commercial value.
as rock salt

Sodium

The most important compound is halite, NaCl, which is found both and in solution in the water of the oceans. Double salts containing sodium, which are insoluble in water and often
8 ),

also in acids (for example, albite, K"aAlSi 3

are very

common,

especially in the group of silicates.

DETECTION.

Sodium

is

usually detected by means of the flame

coloration and alkaline reaction.

compounds color the flame yellow, and the test is exceedingly delicate. The color is monochromatic, and therefore shows only a single band in the spectroscope. The flame color cannot be seen through moderately dark blue glass,
1.

Flame

Test.

Volatile sodium

as the yellow rays are wholly absorbed (see Potassium, p. 105,

* Probirkunst init

1).

dem

Lothrohre.

American translation by Cornwall.

116

REACTIONS OF THE ELEMENTS.

Sodium

a. To illustrate the above, fuse in the forceps some halite or cryolite before the blowpipe, or, still better, fuse some of the material into a loop on platinum wire and introduce it into a Bunsen-burner flame at about the

point
b.

r,

Fig. 35, p. 32.

illustrate the great delicacy of the reaction, heat a platinum wire gives no color to the flame, then draw it through the fingers, heat again, and observe the yellow color which results from the minute trace of sodium derived from contact with the fingers. The flame test is so exceed-

To

until

it

ingly delicate that a great deal of judgment must be exercised in use of it. A mineral should be regarded as containing sodium only gives an intense and prolonged yellow coloration, as in the previous
c.

making when it
test.

from which sodium is not readily volatilized may be fused with gypsum, as directed under potassium (p. 105, 1, c).
Silicates

the exception of the silicates, phosphates, borates, and the salts of a few rare acids, sodium compounds become alkaline upon ignition before the blowpipe.
2.

Alkaline Reaction.

With

kalies
.

similar reaction is obtained from other minerals containing the aland alkaline earths.

a loop about 3 mm. in diameter on platinum wire, fuse some to heat for some time, but not long enough to volatilize all the material. In order to test the alkaline reaction, bring

Make
it,

halite in

and continue

the fused mass in contact with a piece of moistened turmeric-paper on a clean glazed surface. In this experiment, water (one of the products of combustion) acting at a high temperature brings about a partial decomposition of the material, as follows: NaCl NaOH HC1. 2

+H

fused in a loop on platinum 6 ,is 3 wire and heated before the blowpipe, the hydrofluoric acid which is driven off may be readily detected by its pungent odor, or by the reddening of a
b.

If a

fragment of cryolite,

Na AlF

moistened blue litmus-paper held at a little distance beyond the flame, while the residue will impart an alkaline reaction to moistened turmeric-paper.

Strontium,

Sr.

Bivalent.

Atomic weight,
is

87.5.
t

OCCURRENCE. and tite, SrSO

4
,

Strontium
strontianite,

found quite abundantly as celesSrCO but other combinations are

3 ,

rare (brewsterite).

DETECTION.

Strontium

is

usually detected by the flame color-

ation, alkaline reaction after heating,

and by precipitation

as sul-

phate.

Strontium compounds when heated before the blowpipe impart a crimson color to the flame, and this may be ob1.

Flame

Test.

Strontium

REACTIONS OF THE ELEMENTS.

117

tained by igniting fragments held in the platinum-pointed forceps, or often still better by taking up some of the powdered mineral on
'

platinum wire, as directed on p. 35, and heating before the blowpipe or in the Bunsen-burner flame. Often the coloration can be

made more

intense by moistening the material with hydrochloric crimson flame must not be mistaken for lithium, or, in TKe acid. case hydrochloric acid is used, for the yellowish-red of calcium
(p. 59,

2)

which, however,

is

not as persistent on prolonged heat-

ing as the crimson of strontium.

advantage. 2. Alkaline Reaction.

A spectroscope

can be used to

Strontram compounds become alkaline upon ignition before the blowpipe, with the exception of the silicates

and phosphates (compare Calcium, p. 58, 1). A similar reaction is obtained from other minerals containing the alkalies and alkaline earths. There are no lithium minerals known which yield an alkaline reaction after ignition, and therefore a crimson flame in connection with alkaline reaction is an almost certain proof of the
presence of strontium. Strontium sulphate, 8. Precipitation as Strontium Sulphate. SrSO 4 is very insoluble in water and dilute acids, and may be
,

precipitated
tain too

by adding a few drops

acid.

of dilute sulphuric acid to

solutions, provided the latter are not very dilute

and do not condistin-

much

The

test will

be found convenient in

guishing strontium from lithium and calcium, and for the detection of strontium in silicates and phosphates which do not yield
a flame coloration or alkaline reaction (compare Barium, p. 53,
3, b).

Dissolve an ivory spoonful of strontianite in 3 cc. of warm hydrochloric acid, divide the solution into 2 parts, dilute one with about 5, and the other witli 15 cc. of water, and add a few drops of dilute sulphuric acid to each.

In the more concentrated solution, the precipitate forms almost immediafter standing for several minutes, while an exately, but in the other, only made in exactly the same manner with calcite, CaC0 3 would not periment
,

In order in either solution (see p. 59, 3) yield a precipitate of CaS0 4 to precipitate strontium completely as sulphate, it is necessary to add an equal volume of alcohol to the liquid.
.

118
4.

KEACTIONS OF THE ELEMENTS.

Specific Gravity.
specific gravities lie
salts, as

Sulphur

their

Strontium compounds are heavy, and between those of the corresponding calthe following examples show
2.95 3.70
:

cium and barium

Aragonite,
Witherite,

Specific Gravity.

Specific Gravity.

CaCG,
SrCO,,
3 ,

Anhydrite,
Celestite,

CaS0
,

4 ,

2.98
3.96

Strontianite,

SrS0 4
4 ,

BaC0

4.35

Barite,

BuS0

4.48

Atomic weight, 32. OCCURRENCE. In addition to being found native, sulphur also occurs in two very important classes of compounds, the sulphides and sulphates. The sulphides may be generally regarded as salts of the weak acid, hydrogen sulphide, H S, and the common ores of
Sulphur,
S.
a

Bivalent and sexivalent.

many

of the valuable metals are of this class

as argentite,

Ag S
2

galena, PbS; sphalerite, ZnS; cinnabar, HgS,

salts of sulphuric acid,
3 4 ,

etc.

The sulphates are

H SO and the metals calcium, strontium, and lead, form insoluble sulphates, which occur abundantly barium,
Soluble sulphates, especially those of the alkali metals, accumulate in arid regions, and a number of double salts and
basic sulphates are

in nature.

may

known.

Sulphur

tion with a silicate

as in helvite,

Mn

found rarely in combina(Mna S)Be (Si0 ) and noseite,

is
3 4 3

SULPHIDES.
Sulphides may be most conveniently detected by an oxidizing process, such as roasting in the open tube or on char-

DETECTION.

coal.

Oxidation or Roasting in the Open Tube. An exceedingly delicate test for a sulphide is to heat some of the finely powdered mineral in an open tube, when sulphur dioxide, SO,, and usually
1.

an oxide of the metal are formed.

Sulphur dioxide, the anhydride

of sulphurous acid, is a colorless gas, which may be readily detected by its sharp, pungent odor and the acid reaction which it imparts

to a piece of moistened litmus-paper placed at the end of the tube.

According
to the directions given

on

p. 19,

heat about

-fa

of an ivory

spoonful of finely

open tube until the odor of sulphur powdered dioxide (burning sulphur) ceases, and the dark lead sulphide has changed

galena in an

Sulphur

REACTIONS OF THE ELEMENTS.

119
essentially as follows
:

wholly to light-colored lead oxide.

The

reaction

is

PbS

-f-

30

= PbO +

rather volatile

Lead oxide and sulphur dioxide combine to form a and a trace of this will usually be found as a white subproduct,
.

S0 a

limate a

little

above the lead oxide.

The open-tube

test is so delicate that

a minute particle of a sulphide is used, an acid reaction will be imparted to test-paper and usually even the odor of S0 2 will not escape detection.

when

When sulphides of iron, copper, and some other metals are roasted in the open tube, the oxides of the metals which are formed during the operation act as oxidizing agents, and convert some S0 2 to S0 3 , the anhydride of
2FeO S0 3 The formation of S0 3 is sulphuric acid Fe 3 3 -f S0 3 indicated by white fumes passing up the tube, and some of the S0 3 derives sufficient moisture from the atmosphere to form a little S0 4 which cona denses as a liquid in the tube.
: .

2.

Oxidation or JZoasting on Charcoal.

An

excellent

method

for detecting sulphur, but not so delicate as the one just given, is to roast the finely powdered sulphide on charcoal according to the di-

rections given on p. 39,

especially recommended
of sulphur.
3.

and observe the odor of S0 This test is for sulphides which contain a great deal
a.

Roasting in the Platinum Forceps.

Some sulphides oxidize

so readily that,

when held
fire
.

blowpipe, they take a strong odor of S0 a

4.

in the forceps and heated before the and continue to burn for some time, giving Pyrite, FeS 3 and chalcopyrite, CuFeS 2 ,can
,

be tested in this way.

Heating in a Closed Tube.

of their sulphur,

composition when

sulphides suffer no deheated in a closed tube, while others part with

Many

a portion

which condenses on the walls of the tube as a fused sublimate, having a dark amber color when hot, changing to pale yellow and becoming crystalline when cold. A

sulphide of the metal always remains in the tube, and the test, although admirable for some sulphides, is not applicable in all
cases.

Owing

to the air in the tube, there will always be

little
,

some
air

oxidation and formation of a

SO, amount, since there is no free circulation of the and only about one fifth of it is oxygen. be
trifling in

but necessarily this must

Excellent experiments for illustrating the behavior of different sulphides may be made by heating fragments of pyrite, FeS, , and galena, PbS, in

120

REACTIONS OF THE ELEMENTS.

Sulphur

The first gives an abundant sublimate of sulphur, but separate tubes. of iron, FeS, is left in the tube, as may be sulphide proved by removing some of the material and roasting on charcoal or in the open tube. The galena, on the other hand, gives no sublimate, as there is no excess of
sulphur above the normal sulphide, PbS.

Fusion with Sodium Carbonate. When a powdered sulphide is mixed with about 3 parts of sodium carbonate and fused before the blowpipe on charcoal, sodium sulphide will be formed, owing to the strong chemical affinity of sodium for sulphur. If some of the fused mass or of the charcoal into which it
5.

Test on Silver after

placed with a drop of water on a clean silver The test surface, a black stain of silver sulphide will be formed. is so delicate that, if sodium carbonate is heated alone on charcoal
is

has been absorbed

before the blowpipe for a long time with a gas flame, and then placed upon moistened silver, a slight discoloration may result
it is

from the traces of sulphur contained in the gas and charcoal, but not necessary to mistake this slight discoloration for the strong

reaction given by sulphides. If selenium and tellurium are present, the test cannot be relied upon. 6. Oxidation and Solution by Means of Nitric Acid. Nitric acid, owing to its strong oxidizing action, serves as the best solvent
for sulphides.
If hot, concentrated acid is used, there are two pro;

cesses to be considered,

and

(2)

may

products be generally regarded as sulphuric acid and nitrates of the

,

which go on simultaneously solution of the products of oxidation. The

(1)

oxidation,

final

For example, pyrite, FeS, is oxidized to sulphuric anhydride, SO, and ferric oxide, Fe,O and the first of these combines with water to form sulphuric acid, H SO while the second dissolves in the nitric acid to form ferric nitrate, Fe(NO ) Since the metals oxidize more readily than sulphur, it frequently
metals.
, 3 ,

4 ,

8.

happens that a portion of the

a spongy mass.
yellow
if

latter separates in a free state as

is

This separated sulphur oxidizes very slowly, and

is frequently black, owing to some undecomwhich is held mechanically in the sulphur and is posed sulphide, thus protected from the action of the acid. When a sulphide is decomposed with concentrated nitric acid, no volatile sulphur com-

pure, but

REACTIONS OF THE ELEMENTS.

121

pounds are formed, but

all

the sulphur remains either oxidized to

sulphuric acid or partly separated in the free state. While oxidation is going on, the nitric acid must suffer decon>

may take place in different ways for 2HNO,= O + 2NO,+ H,O, or 2HNO = 30 +2NO + H O.
position,
;

but this

example, In either

red vapors of NO 2 will be visible, for, provided the decomposition takes place according to the last equations, the colorless gas, NO, takes on oxygen as soon as it comes in contact with the air, and
case,

Since in the solution of sulphides in nitric acid changes to NO there is no certainty regarding the exact manner in which the acid will break up in order to bring about the oxidation, it is scarcelya.

practical to express the reaction

by means

of equations, but
off, it is

when

red fumes of

NO, gas are abundantly given cation that oxidation is going on.
a.

a sure indica-

illustrate this, treat about \ ivory spoonful of powdered in a dry test-tube with 3 cc. of concentrated nitric acid, and boil pyrite until the evolution of red fumes ceases. The red fumes indicate that an oxi-

In order to

dation

is going on, and, be completely dissolved.

if

the experiment

is

successful, the mineral should

cc. of water,

Dilute the solution with 10

mix thor-

oughly, and test the greater part of it in a separate test-tube with a little barium chloride, when a white precipitate of barium sulphate will be thrown down (p. 122, 1), indicating that sulphuric acid was formed. Dilute the

remainder of the solution

still

further with water, divide into 2 portions,

to p. 85,
4.

and
it

test for ferric

and ferrous iron according

By

this

means

may be proved that the metal, as well as the sulphur, has been converted into the higher state of oxidation.
b.

upon FeS 2 (53.4$

To illustrate the separation of free sulphur, and how this is dependent the character of the minerals, decompose equal portions of pyrite,

in separate test-tubes S), and .pyrrhotite, Fe n S 19 (38.4$ S), with nitric acid, and make the conditions of the experiments as nearly alike Observe that the pyrrhotite with the least sulphur is the most as possible. difficult to dissolve completely, and that by its decomposition sulphur is the pyrite with the most sulphur dissolves completely. separated, while

A possible
to

that pyrrhotite, which is easily soluble in is at S S, non-oxidizing acids (hydrochloric, for example), with evolution of which is instantly oxidized the nitric acid, giving first a S, by

explanation of this

is

decomposed

which is insoluble in non-oxidizing acids, is oxi-f- S; while pyrite, dized by the concentrated acid without any intermediate formation of a S.
2

HO
7.

Solution in Hydrochloric Acid.

Most sulphides are

either

insoluble or difficultly soluble in hydrochloric acid, but those which

122

REACTIONS OF THE ELEMENTS.

Sulphur

hydrogen sulphide gas, 2HC1 = FeCl usually a simple one. FeS

dissolve always give

H S. + H S.
2 a

The reaction Hydrogen

is

sul-

phide

is

readily recognized

by

its offensive

odor.

Treat some finely powdered pyrrhotite, Fe n S lt (almost FeS), in a testtube with 3 cc. of hydrochloric acid, and observe that a gas is evolved which
has a disagreeable odor.

SULPHATES.

DETECTION.

Either the barium chloride

test,

or the one on

sil-

ver after a sulphide has been formed by reduction, may The oxidation and roasting processes used for the detection of sulphur in sulphides cannot be

be used

for the detection of sulphates.

applied to sulphates, as they are already oxidized. If barium chloride 1. Test with Barium Chloride.

is

added to

a dilute hydrochloric acid solution of a sulphate, a white precipitate of barium sulphate, BaSO 4 will form, which is almost abso,

lutely insoluble in water and dilute acids, a very delicate test for sulphates.
If the sulphate proves to
2,

and serves therefore as

be an insoluble one, test according to

or fuse

some

of

it

in a platinum spoon with 6 parts of

sodium

carbonate, soak out the fusion with water, filter, make the filtrate slightly acid with hydrochloric acid, boil, and then test with

barium chloride.
Illustrate the foregoing test by dissolving -J ivory spoonful of gypsum, in warm, dilute hydrochloric acid, and test the solution with 4

CaS0 .2H 2 0,
a
little

barium chloride.
always best to dilute the acids before testing for a sulphate, for if is added to concentrated hydrochloric or nitric acid, barium

It is

barium chloride

chloride or nitrate, both of which are insoluble in concentrated acids,

might be thrown down, and mistaken for barium sulphate. They differ from the latter, however, in that they dissolve readily upon addition of
water.

Test on Silver after Reduction to Sulphide. If a powdered sulphate, mixed with an equal volume of charcoal powder and 2 of
2.

sodium carbonate,

is

made

into a paste with water

and fused on

Tantalum

REACTIONS OF THE ELEMENTS.

123

platinum wire before the blowpipe until effervescence ceases, the sulphate will undergo decomposition and reduction, and sodium
sulphide, ]S"a u S, will be formed. That reduction has taken place may be told by removing the bead from the wire, crushing it, and

placing the material with a drop of water on a clean silver surface. Sodium sulphide will thus react with the silver and make a black
stain of silver sulphide,

as follows

E"a 2 S

+ 2Ag + H O + O =
2

Ag S
2

+ 2NaOH.
it

The

test is exceedingly delicate (see p. 120,

5),

and, although proves the presence of sulphur in a compound, it is not necessarily a test for a sulphate, unless it has been proved

by a previous oxidizing experiment

mineral
,

or

by other means that the

is not a sulphide. As an experiment, test barite, BaS0 4 as directed above. The reaction which goes on during fusion is as follows: BaS0 4 -f- Na a C0 9 -j- 2C = Na 2 S Besides testing on silver, take some of the crushed prod-f- BaC0 3 -f- 2C0 2 uct, resulting from fusion with sodium carbonate and charcoal, and digest
.

it

in a test-tube with a few drops of water, then add a few drops of hydrochloric acid, and observe the odor of the escaping hydrogen sulphide gas, which will serve as a certain proof that the sulphate has been reduced to a

sulphide.
3.

Closed- Tube Reactions.

the alkalies, alkali earths, heated in a closed tube, while sulphates of the less basic elements, such as aluminium, iron, and copper, are more or less decomposed,
,

and

The common sulphates, those of lead, suffer no decomposition when

yielding sulphuric anhydride, SO 3 or sulphurous anhydride, SO 2 , or both. As water of crystallization is usually present in the
latter

compounds,

it is

also driven off

and

is

made

strongly acid

by the oxides

of sulphur (compare p. 82,

2).

Tantalum, Ta.
OCCURRENCE.

Pentavalent.

Atomic weight,

182.6.

Tantalum is associated with niobium in the group of the tantalates and niobates (see Niobium, p. 98). minerals known as DETECTION. There are no simple tests for the detection of tantalum, but if niobium is found in any compound, it is almost certain that tantalum is
also

Tantalates are characterized by high specific gravities, than those of the corresponding niobium compounds. greater In order to make a definite test for tantalum, separate the mixed tantalic and niobic oxides by fusion with potassium bisulphate, and treatment as
present.

124
directed on p. 99,
2.

REACTIONS OF THE ELEMENTS.

Treat the oxides in a platinum dish with a

Tellurtum
little

pure

hydrofluoric acid, filter if necessary, and add a little potassium fluoride. Evaporate the solution in a water-bath nearly, but not quite, to dryness, dissolve the residue in the smallest possible quantity of boiling water, and al-

low the solution to become cold, when, if tantalum is present, a very characteristic double salt, out in fine needles. The crystals, 2 TaF,, crystallizes if collected on a filter-paper and dried, have the appearance of wool. It is necessary that the hydrofluoric acid should be free from hydrofluosilicic acid (alone it should give no precipitate with potassium fluoride), and platinum

or silver vessels

must be used.

Tellurium, Te.
125.

Usually bivalent in minerals.

Atomic weight,

often

Tellurium is found as the native element, but more combined with the metals in tellurides, and it occurs rarely as tellurous oxide and salts of tellurous and telluric acids. The tellurides are analogous to the sulphides, and some of the more important ones are tetradhessite, Ag a Te; altaite, PbTe; sylvanite, (Au,Ag)Te 2 and ymite, Bi,Te s Tellurium is the only element with which gold has calaverite, AuTe a been found in minerals, in chemical combination. DETECTION. A very delicate test for tellurium or tellurides may be
it

OCCURRENCE.
is

made by heating
about 5
cc.

a little of the finely powdered mineral in a test-tube with

of concentrated sulphuric acid, when the latter assumes a beautiful reddish-violet color. After cooling, addition of water will cause the
color to disappear,

and a grayish-black precipitate of tellurium.will be thrown

down. Another
little

test, applicable to all compounds containing tellurium, is to heat a mixture of the finely powdered substance with sodium carbonate and a

dium

charcoal dust, in a rather large closed glass tube, by which means sotelluride is formed, and after cooling and addition of water, the soluIf a

tion will assume a reddish-violet color.

few drops of the solution aro

transferred to a porcelain plate or watch-glass by means of a pipette, the color soons disappears, and a gray precipitate of tellurium forms, owing to the oxidizing action of the air. The color disappears still more quickly if
air is

blown through some of the solution. By heating in the open tube, tellurium and the tellurides are oxidized, and yield TeO,, which passes up the tube as a white smoke, but mostly con-

denses near the heated part as a white sublimate.

volatilizes very slowly, and fuses into globules, and white or colorless when cold.

On

heating the

latter, it

which are yellow when hot,

and condenses on the hot

Heated in the closed tube, tellurium

volatilizes

as fused globules having a metallic luster.

Accompanying the

tellu-

Tin

REACTIONS OF THE ELEMENTS.

125

rium are white or colorless globules of the oxide, TeO a , formed from the oxidation, due to the air in the tube. Heated before the blowpipe on charcoal, tellurium is volatilized, and condenses near the heated part as a white sublimate of Te0 2 , somewhat resem-

Some tellurium may escape oxidation, and condense brownish coating distant from the assay. The sublimates volatilize when heated before the blowpipe and impart a pale greenish color to the reducing flame.
bling antimony oxide.
as a slight

Thallium,

Tl.

Univalent and trivalent.

Thallium
it

Atomic weight,

203.6.

OCCURRENCE.
ite,

is

a very rare element, and thus far only two

minerals containing
rare.

in considerable quantity have been observed, crookes(Cu,Tl,Ag),Se, and lorandite, TlAsS a , both of which are exceedingly

Thallium and its salts are quite volatile when heated beand impart an intense green color to the flame. When the thallium flame is examined with the spectroscope, it shows only one bright green band. Heated before the blowpipe on charcoal in the reducing

DETECTION.

fore the blowpipe,

flame, thallium compounds yield a slight white coating of thallium oxide. Heated on charcoal in the oxidizing flame, with potassium iodide and

sulphur, a yellowish-green coating, resembling lead iodide, is obtained, but this may be readily distinguished from the latter by the flame coloration.

Thorium, Th.
The

Tetravalent.

Atomic weight,

233.

reactions for this rare element are given under Cerium.

Tin, Sn.

Tetravalent in minerals.

Atomic weight,

119.

OCCURRENCE.

Tin

is

SnO
8

Its

combinations

found chiefly as the oxide cassiterite, with sulphur and sulphides of the

metals, the sulpJiostannates (stannite,

Cu,FeSnS

4 ,

and

canfieldite,

Ag SnS ), are Ca(BO) Sn0

6 2

rare.

Nordenskioldine

is,

perhaps, a basic stannate,

4.

Traces of tin are found in

many columbates and

of metal-

tantalates.

lic

Tin is usually detected reduction on charcoal. globules by

DETECTION.

by the formation

If i ivory spoonful of Reduction on Char coal. finely powis mixed with an equal volume of powdered charcoal and 2 of sodium carbonate, made into a paste with water, and then heated on charcoal in the reducing flame, the tin will be read1.

dered tin oxide

126
ily reduced,

REACTIONS OF THE ELEMENTS.

Tin

which are bright when covered with the reducing flame, but become coated with a film of oxide on exposure to the air. If heated intensely before the blowpipe, and for a considerable time, sufficient tin may volatilize to on the give a rather conspicuous white coating of oxide, Sn0

and

collect into globules,

Tin globules are readily fusible, malleable, and, if cut, they show a white metallic color. If treated with a little, moderately concentrated, warm, nitric acid, they do not dissolve, but are
charcoal.

oxidized to a white hydroxide (metastannic acid). Tin must not be confounded with other elements which give metallic globules

be distinguished from lead and bismuth by the absence of a yellow coating of oxide on the charcoal, and from

on

charcoal.

Iv

may

silver

by the coating

of oxide

which forms both on the charcoal

and over the surface of the globules. Sodium carbonate and oxide of tin, when heated together without the addition of charcoal powder, usually form an infusible mass which is very difficult to reduce.
Oxidation with Nitric Acid. The action of nitric acid upon metallic was mentioned in the previous paragraph. Sulphides of tin (the sulphostannates), if pulverized and treated with nitric acid, yield the insoluble metastannic acid, and after evaporating off most of the nitric acid and diluting with water, this may be collected on a filter, washed with water, and
2.

tin

1. tested according to 3. Detection of Small Quantities of Tin.

Mix 1 or 2 ivory spoonfuls of the finely powdered mineral with 6 volumes each of sodium carbonate and of sulphur, transfer the mixture to a porcelain crucible, cover, and heat gently
at

fused mass with

minutes at a red heat. On cooling, treat the water, which dissolves sodium -sulphostannate, while most other substances which are apt to be present will be insoluble. Filter,
first,

finally for five or ten

warm

and by adding sulphuric acid to the filtrate, precipitate the tin as sulphide, which will be accompanied by much free sulphur. Collect the precipitate on a filter, wash several times with water, ignite in a crucible to get rid of the free sulphur and the paper, and test the residue before the blowpipe on
charcoal, according to
1.

If a porcelain crucible

is

not at hand, the fusion

with sodium carbonate and sulphur may be made in a large bulb tube or even in a test-tube. When niobates and tantalates are fused with potassium bisulphate and treated as directed on p. 99, 2, the oxides of tin and tungsten remain with

Titanium

REACTIONS OF THE ELEMENTS.

127

the niobic and tantalic oxides, and these may be separated either by the sodium carbonate and sulphur fusion, or by digestion of the moist oxides with ammonium sulphide. After filtering, precipitate the tin and tungsten

by addition of sulphuric acid,

collect the precipitate

1.

on a

filter,

wash, ignite,

and

test for tin, as directed in

Titanium,

Ti.

Tetravalent and trivalent.

Atomic weight,

48.

Although usually classed among the rare eletitanium is quite common, and is always found in combinaments, tion with oxygen. Kutile, octahedrite, and brookite, which are different crystalline forms of Ti0 2 ilmenite, or titanic iron (a combination of the oxides of iron and titanium); and titanite, CaTiSiO 5
;

OCCURRENCE.

are the

commonest titanium minerals. the form of ilmenite, titanite, or rutile,

rocks.

Some
is

titanium, either in present in most igneous

be detected by the salt of phosphorus bead, the reduction with metallic tin, or oxidation with

DETECTION.

Titanium

may

hydrogen peroxide.
Oxide of titanium, if disTest with Salt of PJiospJiorus. bead in the oxidizing flame, gives a solved in a salt of phosphorus
1.

yellow when hot, and colorless when cold, while in the reducing flame the glass is yellow while hot, but on cooling Since assumes a delicate violet color, due to the presence of Ti a 3
glass

which

is

the color

never very intense, and the presence of other substances which color the bead interferes with it, one of the tests found more satisfactory. given beyond will usually be
is

No
2.

decisive test can be

made with

borax.

readily tains TiCl 4

deduction with Tin. Most titanium minerals are very insoluble in acids, but after fusion with sodium carbonate, they go into solution in hydrochloric acid, and the solution con.

If this acid solution is boiled

,

with a

little

granulated

is reduced to TiCl 3 which causes the solution to tin, the titanium assume a delicate violet color. Other substances with which tita-

nium

and the test is quite delicate, apt to occur do not interfere, but if a substance is supposed to contain less than 3 per cent of the test with hydrogen peroxide is to be preferred.
is

TiO.,

128

REACTIONS OF THE ELEMENTS.

Titanium

To

illustrate this test,

eral (rutile

or ilmenite) with

mix ^ ivory spoonful of the fiwely powdered min6 volumes of sodium carbonate, make into a

either on platinum wire or paste with water, and fuse before the blowpipe Oxide of titanium, which is an acid anhydride, is decomposed charcoal. of sodium titanate, Ti0 2 -{readily by sodium carbonate, with formation Na i.iO 4 -t- ^'C0 2 and the latter is easily dissolved by hydro2Na,CO,

chloric acid.

Na Ti0
4

8HC1

Ti01 4 + 4NaCl

+ 4H

0.

Treat the fusion

5 cc. of strong hydrochloric acid, boil until a solution is obtained, filter if necessary, then add a little granulated tin, and If the quantity of titanium boil until the violet color makes its appearance.
in a test-tube with about
is

small,

it is is

The

color

1 or 2 cc. are left. necessary to boil the liquid away until only and the evolution of seen best when the acid becomes cold,

is present, sometimes boiling, a as oxide, but enough will always remain in portion of it will precipitate solution to give the violet color. In testing niobates and tantalates for titanium, it is best to fuse the material with borax, as directed on p. 98, 1, and on dissolving the fusion

hydrogen

ceases.

If

much

titanium

on

in hydrochloric acid and boiling with tin, the violet color of titanium will appear before the blue of niobium.

Hydrogen Peroxide. For this exceedingly defimust be dissolved in sulphuric acid, which may be accomplished by first fusing with sodium carbonate, as
3.

Test with

cate test, the mineral

previously directed, treating the fusion in a test-tube with 1 cc. of concentrated sulphuric acid and 1 cc. of water, and heating until

the solution becomes clear.

water is added, then some and if titanium is present, the solution becomes hydrogen peroxide, reddish- yellow to deep amber, depending upon the quantity of the

When cold,

titanium in the solution.

Tungsten,
erals

W.

Sexivalent.

Atomic weight,

185.

OCCURRENCE. Tungsten is the acid-forming element in a group of minknown as the tungstates, the most important of which are wolframite, and scheelite, CaW0 The element is hiibnerite, MnW0 (Fe,Mn)M found in small quantity in a number of the niobates and tantalates.
/r

4 ;

4 ;

DETECTION. 1. When a tungstate is decomposed by boiling with hydrochloric acid, an insoluble, canary-yellow, tungstic oxide, WO, , is obtained, and if after the addition of a little granulated tin, the boiling is continued,
a blue color
is

at first obtained

(2WO,

finally changes to

brown (WO,).

4- W0 9 ), and this by further reduction Another very good way to test, after
is

having decomposed the mineral with hydrochloric acid,

to collect the

Uranium

REACTIONS OF THE ELEMENTS.

129

W0

acid,

on a filter, dissolve some of it in ammonia, acidify with hydrochloric which usually causes a white or yellowish turbidity, and then boil
tin.

with granulated
water,
2.

when

it

will be
it is

bium), and that

When a "blue color has been obtained, dilute with found that the color does not disappear (compare Niodue to an insoluble compound suspended in the liquid.

If the tungstate is insoluble or difficultly soluble in hydrochloric acid (wolframite), mix the fine powder with 6 volumes of sodium carbonate, make

into a paste with water, fuse in a loop on platinum wire, pulverize, and dissolve in a test-tube in a little water.

The sodium

tungstate formed during

soluble in water (difference from niobium); it may be separated from the bases by filtering, and, on acidifying the filtrate with hydrochloric acid and boiling with tin, the blue reduction test may be obtained. 3. In the salt of phosphorus bead in the oxidizing flame, oxide of

fusion

is

tung-

sten gives no color, but in the reducing flame, the bead becomes fine blue. The reactions with borax are not satisfactory.

In order to detect the small quantity of tungsten in niobates and tantalates, treat the oxides obtained by the potassium bisulphate fusion (p. 99, 2) either with ammonium sulphide or a sodium carbonate and
4.

sulphur fusion, separate the tungsten exactly as described for tin 3), and then test by the foregoing methods.

(p. 126,

Uranium, U.
240.

Tetravalent and sexivalent.

Atomic weight
in

OCCURRENCE.

This rare element

is

found as an essential constituent

only a few minerals (uranite, gummite, uranosphaerite, torbernite, autunite), while it occurs sparingly in a number of others, especially those con taining the rare elements niobium, tantalum, thorium, zirconium, cerium^

lanthanum, didjfffiium, yttrium, and erbium; as fergusonite, samarskite, euxenite, and polycrase. DETECTION. 1. The reactions with the salt of phosphorus bead usually In the oxidizing flame, the oxide is solserve for the detection of uranium. uble to a clear yellow glass, which becomes yellowish-green on cooling, while after heating in the reducing flame, the bead assumes a fine green color. With borax, the colors are not so decisive, and are nearly like those of iron,

when
less.
2.

being in the oxidizing flame reddish-yellow when hot, fading to. yellow cold, and in the reducing flame, very pale green, fading to almost colorIn the presence of other elements which impart color to the
fluxes,

for the detection of small quantities of uranium in minerals, it is best to proceed as follows : Make a solution in hydrochloric acid (after fusion with sodium carbonate, if necessary, as directed under silicates, p. 110, 4,

and

or with borax, as directed under niobates, p. 98, 1), nearly neutralize the excess of acid with ammonia, add solid ammonium carbonate, shake

130

REACTIONS OF THE ELEMENTS.

Vanadium

is

The uranium vigorously, and allow the liquid to stand for a few minutes. at first precipitated, but is soluble in an excess of the ammonium carbon-

ate, and by filtering may be separated from a great many elements which are precipitated by that reagent. Sometimes there is difficulty in obtaining a clear filtrate, and, if go, a few drops of ammonium be added

with the

ammonium

uranium on a filter, and test it with a salt of phosphorus In case the precipitate is small, burn the paper containing it in a crucible, and test the residue.
bead.

acid, boil to expel itate containing

sulphide may Make the filtrate containing the uranium carbon dioxide, add ammonia in excess, collect the precipcarbonate.

Vanadium, V.
OCCURRENCE.
salts of

Usually pentavalent.

Atomic weight,

51.4.

Vanadium

is

is closely related chemically to phosVanadinite, Pb 4 (PbCl)(V0 4 ) 3 , and descloizite, phoric and arsenic acids. Pb(PbOII)V0 4 are the commonest vanadates.
3 4,
,

vanadic acid,

H V0

a rare element found in the vanadates, or

which

1. Vanadium is usually detected by the color it imparts to With borax, in the oxidizing flame, the bead is yellow when hot, changing through yellowish-green to almost colorless when cold. In the reducing flame, it becomes dirty green when hot, changing to fine green when cold. In the salt of phosphorus bead, the color in the oxidizing flame

DETECTION.

the fluxes.

yellow to deep amber, fading slightly on cooling; while in the reducing it becomes an indistinct dirty green when hot, changing to fine green on cooling. The amber color with salt of phosphorus, in the oxidizing
is

flame,

flame, serves to distinguish vanadium from chromium. 2. To detect small quantities of vanadium, and in cases where other sub-

stances are present which impart color to the fluxes, proceed as follows: Fuse the powdered mineral in a platinum spoon with about 4 parts of sodium carbonate and 2 of potassium nitrate, and digest the fusion with warm
water, in order to dissolve the soluble alkali vanadate. Filter, acidify the with a slight excess of acetic acid, and add a little lead acetate, which will precipitate a pale yellow lead vanadate (lead chromate, p. 70,
filtrate
3, is

much

yellower).

Some

may

then be tested with a

salt of

of the precipitate collected on a filter-paper phosphorus bead.

Yttrium, Y.

Trivalent.

Atomic weight,

89.
rare earth

For the reactions

metals
(p. 65).

of this rare element, see

Cerium and the

Zinc, Zn.

Bivalent.

Atomic weight,

65.4.

OCCURRENCE. Zinc occurs most abundantly as sphalerite, ZnS, and in addition to this, smithsonite, ZnCO, willemite, Zn SiO ;
; 2

Zinc

KEACTIOJsS OF THE ELEMENTS.

131

calamine (ZnOH) a SiO 3 and zincite, ZnO with MnO, occur in sufficient quantities to be mined as ores of the metal. Zinc is also
;

found in a number of other minerals, franklinite, gahnite, aurichalcite, and in small quantity in many sulphides.
Zinc volatilizes when heated before the blowpipe, detected by the coating of oxide on charcoal, and usually also by the test with cobalt nitrate and the flame coloration.

DETECTION.
is

and

I.

Reduction of Zinc

to the

Metallic State

and Formation of a

Coating of Oxide.
follows
:

The best method

for the detection of zinc is as

the finely powdered mineral with about j- volume of little sodium carbonate, and make into a paste with water.

Mix

of this mixture is then taken

up

in a small loop

on

fine plat-

inum wire and heated

intensely, holding the loop about 10

49.

mm.

from a piece of charcoal, somewhat as represented by Fig. intense heat and strong reducing action are necessary to bring about reduction to the metallic state and
volatilization

An

of

the zinc.

The

metal thus volatilized takes oxygen from the air and collects as a

ZnO, which is pale canary-yellow when hot and white

coating
of

when
where
coal,

cold.

The coating
is

is

near

the heat strikes the char-

and

not volatile in the

oxidizing flame. If the coating is made to deposit on a piece of charcoal previously moistened with cobalt nitrate, the zinc oxide

have a green color which is especially characteristic. For a proper understanding of this test it must be borne in mind that the method demands the reduction of zinc to the metallic state, but no globules form, for, as fast as reduced, the metal
will
volatilizes.

reduced, and the coating of oxide obtained without the use of a flux, when a fragment of

From many compounds,

zinc

may be

132

REACTIONS OF THE ELEMENTS.

Zinc

the mineral (about 2 mm. in diameter) is heated very hot on charcoal in a reducing flame, but some skill in manipulating the flame

needed in order that the fragment shall not be blown away. A good way to make the test is to take the fragment in the platinum forceps, and holding the latter against a piece of charcoal so
is

that the assay is about 5 mm. from the surface, heat at the tip of the blue cone, as shown in Fig. 49. a. In order to make a zinc oxide coating on charcoal, mix finely powdered calamine, (Zn.OH).,Si0 3 with J volume of sodium carbonate, take up in a small loop on platinum wire and heat intensely, as directed. In this experiment the sodium carbonate answers a double purpose: it serves to hold the material on the platinum wire, and also to decompose the silicate, forming sodium silicate, thus setting free zinc oxide, which may be readily Na a C0 3 = 2ZnO Na a Si0 8 CO, reduced. (Zn.OH) a SiO H,0.
,

~b.

flux,

In order to produce the coating of zinc oxide without the use of a experiment with fragments of smithsonite or sphalerite. With the lat-

ter mineral, the

oxygen of the

air converts ZiiS to

is

ZnO, and by the reducing

action of the flame, zinc oxide

changed

to metallic zinc.

NOTE.

In the presence of lead, bismuth, cadmium, or antimony, which

also give coatings of oxide on charcoal, the test for zinc with cobalt nitrate should not be made until the coating has been heated for some time in the

oxidizing flame, in order to volatilize the oxides of the metals mentioned. In the presence of much tin, it is difficult to recognize zinc with certainty by the reaction on charcoal, as tin also gives a white coating of oxide,

which when ignited with cobalt nitrate gives a bluish-green color. If, however, the mineral is decomposed by nitric acid (stannite), the test may be made as follows Treat with nitric acid, and separate the tin according to p. 2, then to the filtrate add solid sodium carbonate until the acid is 126, neutralized, and a permanent precipitate forms, heat to boiling, filter, and wash once with water. The precipitate will contain all the zinc, and probably basic carbonates of other metals, and a portion of it, mixed with sodium
:

carbonate,
2.

may be

tested on charcoal for zinc.

minerals, metallic zinc is produced by heating in the platinum forceps in a strong reducing flame, and the metal, as it volatilizes and passes into the air, burns with a vivid, pale, bluish-green light, appearing usually as streaks in the
Test.

Flame

From some

The experiment does not succeed well outer part of the flame. when too small a fragment is used, and it is best to take one about 3 mm. in diameter.

Zirconium

REACTIONS OF THE ELEMENTS.

133

When the Experiments may be made with smithsonite and sphalerite. former is used, the zinc carbonate changes readily to oxide, and, by reduction, metallic zinc is slowly formed. converted by oxidation to zinc oxide,

With sphalerite, the assay must be first and then by reduction to metallic zinc,

but usually a point can be found a little beyond the blue cone of the blowpipe flame, where oxidation and reduction go on simultaneously, and a continuous zinc flame can be maintained.
3.

when moistened with

color,

Some zinc minerals, Heating with Cobalt Nitrate, Co(NO ) cobalt nitrate and heated, assume a green but this simple test can be applied only to infusible, white or
3

a.

light-colored

compounds or those which become

test,
it is

so on ignition.

In making the

be used, but

a fragment held in the platinum forceps may usually better to make the finely powdered min-

eral into a paste

with cobalt nitrate, and then to heat on charcoal

in an oxidizing flame.

when similarly treated, usually show a blue the formation of a fusible cobalt silicate. If an color, owing to experiment is made with a large fragment of calamine, it will someSilicates of zinc,

times show blue where the heat was most intense, and green at
other parts.
indicated

Change of Color upon Heating. The presence of zinc is often by the change of color of the assay when heated i.e., to straw or pale canary-yellow when hot, becoming white when cold. This test can, of course, be applied only to compounds which are
4.
;

white or light-colored.
Zirconium, Zr.
OCCURRENCE. some regions,
Tetravalent.

Atomic weight,

90.7.

Although a rare element, zirconium is found abundantly in especially as zircon, ZrSi0 4 , which, in small quantities, is almost an unfailing constituent in granites and rocks rich in alkalies. It is found in a number of rare minerals, examples of which are baddelyite, Zr0 2 ,
etc. eudialyte, catapleiite, wohlerite, polymignite, DETECTION. Zirconium gives no very characteristic tests which serve for
its

A solution must first be obtained, which quick and sure identification. is accomplished by fusing with sodium carbonate, and treatment as usually The decomposition, however, is not directed under silicates (p. 110, 4). a portion of the zirconium will be obtained in complete, and usually only The simplest test is with turmeric-paper, which, when placed in a solution.

134

REACTIONS OF THE ELEMENTS.

Zirconium

hydrochloric acid solution containing zirconium, assumes an orange color. As the color is not very marked, it is best to make a comparison by taking

one containing turmeric-paper wet by the solution containing and the other a paper wet by acid of about equal strength. zirconium, Ammonium, sodium, and potassium hydroxide throw down zirconium hydroxide as a bulky, gelatinous precipitate, insoluble in an excess of sodium and potassium hydroxides, thus differing from aluminium and beryllium. The precipitate is filtered, washed with water, dissolved in a little hydrochloric acid, the solution evaporated until only a drop or two of the acid remains, the residue dissolved in water, and oxalic acid added, when, if zirconium alone is present, either no precipitate forms, or, if it does form, it goes almost immediately into solution (difference from the rare earth metals, A portion of zirconium hydroxide found cerium, lanthanum, etc., p. 65). test to contain no rare earth metals, or separated from them by the previous by means of oxalic acid, may be scraped from the filter-paper, and dissolved

two

test-tubes,

in the least possible

amount

of dilute sulphuric acid

to the solution, pot-

then added until a precipitate forms, afterwards dilute acid is added a drop at a time, until the solution clears (if caresulphuric fully done the liquid at this point will be nearly neutral, and the volume should be small); finally, a little more than an equal volume of a boiling,
assium hydroxide
is

saturated solution of potassium sulphate is added, which on standing precipitates a double zirconium potassium sulphate as a white powder, and

complete.

serves as a characteristic test for zirconium, although the precipitation is not If the precipitate is filtered, and washed with a cold and satu-

warm hydrochloric zirconium hydroxide may be precipitated by means of ammonia. acid, pure On ignition, zirconium hydroxide yields the oxide Zr0 2 , and this, if pulverrated solution of potassium sulphate, then dissolved in
ized, mixed with cobalt nitrate, and ignited before the blowpipe on charcoal, assumes a lavender or bluish slate-color.

CHAPTER

IV.

TABULATED ARRANGEMENT OF THE MORE IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

THIS chapter
tation of
analysis.

unknown

intended to be used especially for the interprereactions which are encountered in blowpipe The tests, if made in the order given below, will serve as
is

a systematic course of qualitative blowpipe analysis in examining

unknown

substances.
:

A. Heating in the platinum forceps

Flame

coloration, p. 135.

B. Heating in the closed tube, p. 137. C. Heating in the open tube, p. 140.

D. Heating on charcoal, both with and without fluxes, p. 142.

E. Treatment with cobalt nitrate, p. 146. F. Fusion with the fluxes on platinum wire
:

Borax,

p.

148

phosphorus salt, p. 149 G. Treatment with

reagents, p. 151.

and sodium carbonate beads, p. 151. acids, and reactions with the common

A. HEATING IN THE PLATINUM FORCEPS

FLAME COLORATION.

Suggestions concerning the use of the platinum forceps and the methods of heating substances in them have been given in Chapter

In testing minerals, any change which the material undergoes should be carefully noted, but for the identification of the elements, flame colorations are the most important. The colors
II,

p.

15.

may

often be obtained best

p. 35.

by heating on platinum
is

wire, as sug-

gested on

If a black,

magnetic globule or mass

it

obtained after heating

135

in the reducing flame,

usually indicates iron, less often cobalt

136

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

If the mass left in the forceps after or nickel. heating before the blowpipe gives an alkaline reaction when placed on moistened turmeric-paper, it indicates the presence of an alkali or

alkaline earth; as sodium, potassium, calcium, strontium, 'barium,

and possibly magnesium.

TABLE OF FLAME COLORATIONS.

Color.

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

137

TABLE OF FLAME COLORATIONS.

Color.

Continued.

138

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

is

and

seen best in a dark room.

fire.

A very few minerals

glow, as

if

they had taken

4.

CHANGE OF COLOR.

Materials

often change color after

heating, owing to decomposition. Again, without any change in chemical composition, some substances when hot assume colors

from those they have when cold. The changes are very numerous, and only a few of the more important are given.

which are

different

TABLE GIVING CHANGE OF COLOR IN SUBSTANCES IN THE CLOSED TUBE.

WHEN HEATED

Original Color.

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

139

described on p. 100, 1. Formed when some higher oxides, those of manganese, are heated. especially

AMMONIA, NH Colorless, with characteristic odor. HYDROFLUORIC ACID, HF. Colorless, with pungent odor, etching of the glass, and strong acid reaction. From compounds
4.
8.

5.

containing fluorine with hydroxyl

6.

(p. 77,

5).

NITROGEN DIOXIDE,
nitrates.

NO

a.

Red

vapors, with pungent odor.

From
7.
8.

BROMINE, Br.
IODINE,
I.

vapors, with pungent odor. Violet vapors, often accompanied by crystals of

Red

iodine.
9. BROWN SMOKE, accompanied by dark and empyreumatic odor. Organic material.

distillation

products

c.

The Formation of Sublimates which Condense on

of the Tube.

the Walls

TABLE OF SUBLIMATES PRODUCED IN THE CLOSED TUBE.

Color and Condition.

140

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

Continued.

TABLE OF SUBLIMATES PRODUCED IN THE CLOSED TUBE.

Color and Condition.

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

a.
b.

141

Odors.

The formation of sublimates which condense on the walls

of

the tube.
c.

The character

of the residues.

a.
1.

Odors.

ODOR OF BURNING SULPHUR.

and formation

Very strong and pungent,

due

to oxidation

of sulphurous anhydride,

SO

2.

piece of moistened, blue litmus- paper placed in the upper end of the tube is reddened, owing to the acid character of S0 2 If prop.

erly oxidized, no sublimate of sulphur is formed. The test is exceedingly delicate, and is useful for the identification of sul-

phides.

from

Observed when arsenic is driven off rapidly and is not completely oxidized. compounds, A peculiar odor, learned only by ex3. ODOR OF SELENIUM. Obtained when selenium is volatilized from its comperience.
2.

GARLIC ODOR.

its

pounds and not wholly oxidized. 4. ODOR OF OSMIC OXIDE. Very pungent.
b.

Sublimates.

TABLE OF SUBLIMATES PRODUCED IN THE OPEN TUBE.

Color and Character.

142

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

Continued.

TABLE OF SUBLIMATES PRODUCED IN THE OPEN TUBE.

Color and Character.

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

b.
c.

143

Sublimates.

The formation

of metallic globules or of a magnetic mass.

etc.

a.
1.

Odors.

ODOR OF BURNING SULPHUR.

Obtained by roasting

sul-

phides in the oxidizing liame. Obtained by heating native arsenic and 2. ODOR OF GARLIC.
peculiar odor, which must be learned by experience. Obtained when selenium is volatilized from its compounds in the reducing flame.
b.

arsenides in the reducing flame. 3 ODOR OF SELENIUM.

Sublimates.

TABLE OF SUBLIMATES PRODUCED ON CHARCOAL.

Color and Character.

144

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

TABLE OF SUBLIMATES PRODUCED ON CHAUCOAL.

Color and Character.

Continued.

IMPOKTANT BLOWPIPE AND CHEMICAL REACTIONS.

145

TABLE OF SUBLIMATES PRODUCED ON CHARCOAL.

Color and Character.

Continued.

146

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

;

lead deposits on the charcoal

the metal has a lead-gray color,

and

is soft

and malleable.
Easily fusible;

bright when in the reducing flame, but oxidizing on exposure to the air a yellow coating of oxide of bismuth deposits on the charcoal the metal has a lead5.

BISMUTH.

and is brittle, although gray when hammered. extent

color,
6.

it

may

at first flatten to

some

bright when in the reducing flame, but oxidizing on exposure to the air a white coating of oxide of tin deposits on the charcoal if the globule is heated intensely
TIN.

Easily fusible

the metal has a white color, and

7.

is soft

and malleable.

EASILY FUSIBLE G-LOBULES with metallic luster, bright when in the reducing flame, but tarnishing on exposure to the air,
are frequently obtained when combinations of the metals with These sulphur, arsenic, or antimony are heated on charcoal.

globules of sulphide, arsenide, or antimonide of the metals may usually be distinguished from pure metals by their brittleness.
8.

MAGNETIC GLOBULES

or a magnetic mass will be obtained

substances containing iron, less often cobalt and nickel, are fused with sodium carbonate on charcoal.
9.

when

ALKALINE REACTION.
flux,

Provided sodium carbonate has not

a mass or residue, which, after strong ignition, gives an alkaline reaction when placed upon moistened turmeric-paper indicates one of the alkalies or alkaline earths;

been used as a

as sodium, potassium, calcium, strontium, barium,

and possibly

magnesium.
10.

BLACKENS SILVER.

After fusion with sodium carbonate

in the reducing flame and placing upon a clean, moistened silver surface, if a black stain is produced, it indicates some compound

of sulphur

(p. 119,

5,

and

p. 122,

2).

E.

TREATMENT WITH COBALT NITRATE.

of testing with cobalt nitrate has been given on

The method
p. 29.

It is applicable
is

pounds, and

only to infusible and light-colored com especially useful in detecting zinc and aluminium.

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

147

TABLE OF REACTIONS WITH COBALT NITRATE.

Color.

148

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

a.

Fusion with BORAX on Platinum Wire.

TABLE OF REACTIONS OBTAINED WITH BORAX.

Oxidizing Flame.

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

149

TABLE OF REACTIONS OBTAINED WITH BORAX.

Oxidizing Flame.

Continued.

150

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

TABLE OF REACTIONS OBTAINED WITH PHOSPHORUS SALT.

Oxidizing Flame.

Confd.

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

151
ConVd.

TABLE OF REACTIONS OBTAINED WITH PHOSPHORUS SALT.

Oxidizing Flame.

152
2.

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

HYDROGEN SULPHIDE,
Cl.

H S.
a

Colorless,
7).

with disagreeable

odor.
3.

Obtained from sulphides

(p. 121,

CHLORINE, Nearly colorless, with disagreeable odor. Obtained from a few higher oxides when dissolved in hydrochloric
acid
4.

(p. 101,

2).

NITROGEN DIOXIDE, nitric acid when oxidation

N0
is

a.

Dark red vapors derived from

(p. 120,
6).

taking place

b.

Color of the Solution.

ones will

A great variety of colors may be obtained, but only the common

be mentioned.
1.

AMBER TO BROWNISH-RED.
GREEN.

Hydrochloric acid solutions

containing ferric iron.

2.

nickel.

From mixtures of copper and iron, and also from Addition of ammonia in excess gives a blue color with copintensified

per and nickel, the former being more intense.

BLUE. From copper, and greatly excess of ammonia.

3.

by adding an

4.

PINK OR PALE ROSE.

From

cobalt.

c.

Insoluble Residue after Decomposing a Mineral.

obtained by evaporation of a solution, and is insoluble upon subsequent addition of water or acid, it indicates a silicate (p. 108, 1).
1.

JELLY.

When this is

2.

PULVERULENT RESIDUE.
2).

in the acid than the original

White, but more transparent powdered mineral it may indicate

;

silicate (p. 109,

3.

WHITE

RESIDUES.

These

may

be obtained when minerals

containing
nitric acid.

tin,

antimony, and sulphide of lead are oxidized by

indicate tungsten. spongy mass or fused globule of sulphur is also often obtained when sulphides are treated with nitric acid (p. 120, 6).
4.

A YELLOW

RESIDUE.

This

may

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

153

d. Precipitation

by Adding Appropriate Reagents

Solution.

to the

Clear

Only those reagents which are most useful in making simple test-tube
experiments will be mentioned.
1.

AMMONIA

mium
(p. 65),

precipitates aluminium, beryllium, bismuth, chro(trivalent), iron (ferric), lead, and the rare earth metals

as hydroxides.
variety of conditions, especially

Under a
licic,

when phosphoric,

arsenic, si-

and hydrofluoric acids are present, many other elements may be precipitated ; e.g., calcium phosphate is precipitated when ammonia is added to an acid solution of apatite (p. 60, 4, #).
2.

AMMONIUM CARBONATE

is

especially convenient for precipi-

tating calcium, strontium, and barium carbonates from solutions made alkaline by ammonia. 3. AMMONIUM Ox A LATE is useful for the precipitation of cal-

cium oxalate from solutions made alkaline by ammonia. Barium and strontium are also precipitated. 4. AMMONIUM SULPHIDE precipitates, from solutions which are nearly neutral or alkaline, iron, zinc, manganese, cobalt, and nickel, as sulphides, and aluminium, chromium, and the rare earth
metals, as hydroxides.
It is also useful for dissolving freshly pre-

cipitated sulphides of arsenic, antimony,

and tin. 5. BARIUM CHLORIDE precipitates barium sulphate from acid solutions, and serves, therefore, as a very delicate test for a sul6.

phate.

HYDROCHLORIC ACID

precipitates silver, lead,

and mercu-

rous chlorides from

7.

nitric acid solutions.

HYDROGEN SULPHIDE

gas,

when

led into hydrochloric or

sulphuric acid solutions, precipitates silver, lead, mercury, copper,

bismuth, cadmium, arsenic, antimony, and tin, as sulphides. If the solution is in nitric acid, it is best to evaporate in a casserole with sulphuric acid, until the nitric acid is expelled, and then,
after dissolving in water, to run in the

hydrogen sulphide

gas.

154
8.

IMPORTANT BLOWPIPE AND CHEMICAL REACTIONS.

SILVER NITRATE precipitates silver chloride, bromide, or iodide from solutions of chlorides, bromides, or iodides, in water or
dilute nitric acid.
9.

SODIUM CARBONATE

precipitates iron, zinc, manganese, co-

bait, nickel, copper,

magnesium, and many other metals, as basic

or normal carbonates.

SODIUM HYDROXIDE precipitates iron, manganese, cobalt, nickel, copper, bismuth, cadmium, magnesium, and the rare earth metals, as hydroxides, some of these only in the absence of ammo10.

nium
11.

salts.

SODIUM PHOSPHATE

is

useful for detecting

solutions which are not precipitated

carbonate, or have been filtered

magnesium in ammonia and ammonium by from the precipitates produced by

these reagents.
precipitates lead, barium, strontium, and calcium sulphates, the last, however, only when the solutions are
12..

SULPHURIC ACID

concentrated.

CHAPTER

Y.

PHYSICAL PROPERTIES OF MINERALS.

IN the foregoing chapters, minerals have been regarded from the standpoint of their chemical composition only, but they possess in addition certain pliysical properties which may be very useful for their identification and recognition. The most important of these are crystallization, luster, color, hardness, fusibility,

and

specific gravity.

CRYSTALLOGRAPHY.*
Crystallization.

When

a mineral

or

chemical

compound
;

assumes a solid form, it does so by separation from a solution, or from a molten mass, or by condensation from a vapor and the
molecules, or smallest particles of the substance, generally assume a definite arrangement. This process is called crystallization, and

takes place under favorable circumstances it gives rise to crystals, or solids which have not only definite internal structure or arrangement of the molecules, but also definite shapes
it

when

crysto the chemical molecules, but are they may correspond probably larger, and aggregates of them ; and certainly in all instances they are excessively minute. It is a very important proptals
:

bounded by flat surfaces. Yery little is known concerning the molecules which form

erty of crystals that, during their growth, the molecules of the substance tend to arrange or group about themselves only those of
Owing to limited space, this important subject will Lave to be treated in a somewhat elementary manner, but it is hoped that the essential features can be presented with sufficient clearness to enable the student to become familiar with the more important, simTo obtain a really satisfactory knowledge of the ple, crystalline forms and combinations.
subject
it is

quite essential to supplement the text

by a

collection of crystals or models.

155

156

CRYSTALLIZATION".

the

same Tcind.

The

crystallized condition of a
its

compound is,

there-

fore,

one of the very best proofs of

solids

homogeneous character and

purify.

with plane surfaces may result from the arrangement of particles of the same kind is shown by Fig. 50, which rep-

That

FIG. 50.
Cube, octahedron, and dodecahedron made by the regular arrangement of shot. The arrangement of the shot is identical in the three models, but different layers of shot constitute the outer or limiting
surfaces.

resents geometrical shapes

If the shot

regular arrangement of shot. were so exceedingly small that the individual ones could not be seen, the outer surfaces of the solids would appear

made by a

perfectly smooth

however, somewhat misleading, since the shot are in contact with one another, while in crystals the distances between the molecules are probably
flat.
is,

and

Such an arrangement

considerably greater than the diameters of the molecules themmore correct idea, therefore, of an arrangement of moleselves.

cules in a crystal

may

be gained from Fig.

51.

In a crystal the

all of the same kind, and in any given direction they must be equally distant from one another. As in an orchard where the trees are evenly spaced one may look in different directions, a&, a<?, af, etc., (Fig. 52), and seethe

molecules are

through a regular arrangement of particles, as in there are certain definite directions in which the particles Fig. 51, The crystal faces correspond to molecular planes, lie in planes.
trees in rows, so

and have

definite inclinations or angles,

depending upon the mo-

lecular arrangement.

will

Provided a crystal has not been hindered in its development it be bounded by flat surfaces, which give it a regular external

CRYSTALLIZATION.

157
It is

form, and this

is

one of

its

most striking

features.

only occa-

without interruption, for or grows against some obusually by others, stacle so that only a portion or perhaps nothing of its characteristic external form is produced. Even when the external form is
it is

sionally, however, that a crystal develops

interfered with

wholly wanting, the crystalline nature of a substance, due to the regular arrangement of the molecules, may be revealed by some of the physical properties peculiar to crystals. Thus by the aid

3
-!-;*-

44-

-6
FIG. 51.

FIG. 52.

of polarized light it could instantly be told that a transparent fragment of quartz possessed a crystalline structure and was not a bit
of glass.

Most minerals have been observed in a crystallized condition, and it is important to bear in mind that only definite chemical

compounds possess
Constancy

this peculiar property of crystallization. of the Interfacial Angles of Crystals. One

of

the most important features of crystals is that those of the same substance invariably exhibit the same angles between similar
faces.
It is

evident that in an orchard one must look in definite

directions,

ab, of, ag, etc. (Fig. 52), to see the trees in rows, these directions depending upon the way in which the trees are planted. In Fig. 52 the trees are represented as equally spaced along the rows ab and ag, with these rows at right angles to one

another.

It

must

also follow that constancy of interfacial angles

is a feature of crystals, provided each substance has its

own

defi*

158

GONIOMETERS.

nite molecular structure (Fig. 51),

and that the faces correspond to

layers of molecules.

Goniometers.

Instruments for measuring the interfacial an-

gles of crystals are called goniometers. The reflection goniometer consists of a divided circle turning

and provided with devices and adjusting crystals so that the edge between the faces to be measured can be made to coincide with, and be

upon an

axis,

for holding

paralled

to,

the axis of the instrument.

I

Rays

of light

(Fig. 53), either

coming from

a distant object, or made parallel by passing through a lens, fall upon the face ac
of a crystal,

and some

of

them

are reflected

in the direction of the observer

ce.

It is evident that in order to

c&, it will

obtain a reflection in a similar direction from the face

be

necessary to turn the crystal

through the angle /?, which is the supplement of the angle ac5, the angles being read from a divided Measurements can thus be made with great accuracy even circle.

on very small crystals. In studying and calculating the mathematical relations of crystal faces, the supplement angles are much

more convenient

to use than the actual ones,

and are almost

in-

crystallographers. contact goniometer, designed inexpensive consists of a graduated semicircle

variably employed

by

An

by the author,

(Fig. 54) printed

on cardboard, and

provided with a

of transparent celluloid

measuring arm which is

swiveled by means of an eyelet exactly in the center of the arc.

A fine line,

scratched on the under

arm and and in exact alinement blackened,

surface of the celluloid
to indicate the angle.
FIG. 54. (About natural size). with the center of the eyelet, serves In using the instrument the edges of the

CRYSTALLOGKAPHIC AXES.

159

card and measuring arm are brought as nearly as possible in contact with the crystal faces, care being taken that the plane of the card is held at right angles to the edge formed by the intersection
of the crystal faces.

In order to show the relations of Crystallographic Axes. faces it is convenient to take certain directions within the. crystal
crystals as axes.

Usually three are chosen (Fig.

-b,

going from front to back, another b

third c
-<?,

one a -a, from right to left, and a

55),

vertical.

Positive

negative directions are assumed

from the

Crystal faces intersect these axes, and, by measuring appropriate interfacial angles, the relative lengths of the axes, or their ratio to one another, can be de-

center, as indicated

m me figure.

termined.
+ c

For example, sulphur crystals have the form of a pyra-

-c

FIG. 55.

FIG. 56.

FIG. 57.

mid

and the angles which are measured over the edges the a and &, and the b and c axes, respectively, equal 36 joining From these angles it can be calculated, by simple 40?' and 94 52'.
(Fig. 56),

mathematical processes, that, if the length ob is assumed as unity the lengths oa and oc are 0.813 and 1.903, respectively. Designat^

ing the lengths of the axes oa, ob, and oc as a, &, and c, the foregoing mathematical relation can be expressed as follows a b c = 0.813 1 1.903. This is known as the axial ratio of sulphur.
: :

When the
gles
or,

/?,

and y

axes are not at right angles to one another the an(Fig. 57) must be determined.

160

PARAMETERS.

Parameters.
(Fig. 56), at oa, ob,

Parameters are the distances from the center o which crystal faces intersect the axes. For example,
of the face abc.
If oa, ob,

and oc are the parameters

and oc

correspond to the characteristic lengths of the respective axes of

any mineral, the

eters
It

face in question is then said to have the param-

c.

must be distinctly borne in mind that the parameter distances oa, ob, and oc, or the axial lengths, are not expressed in
terms of any unit of measure, but have only relative values. For example, no matter what length is chosen for the b axis, if a and

have relatively the lengths that have been determined for sulphur, a b c = 0.813 1 1.903, then the eight plane surfaces which
c
:
:

intersect the extremities of the a,

b,

and

axes will form a pyra-

mid

(Fig. 56)

whose

interfacial angles will be like those of a sul-

phur

crystal.

Law

of Definite Mathematical

Ratio,

It is

a very impor-

tant feature of crystals that their faces, prolonged if necessary, will intersect the axes only at the ratio distances a, b, and c,
characteristic of each substance, or at simple multiples, or fractions, of these ratio distances.

A plane may, however, be parallel to one or two of the axes, which is indicated by the sign of infinity. Given the axes a -a, b -b, and c -c (Fig. 58) of the ratio lengths
any substance, then possible crystal faces might have the parameter relations a b c, 2a:b c, a b %c, etc. or oo a b c, oo a oo b c, etc. Experience has shown, moreover, that the multiples at which the character istic axial lengths are cut, are most often unity (not expressed before the letters) and infinity, or such simple quantities as 2, 3, J, or When no
characteristic for
: : \ : : , :
: : :
.

sign

is

expressed, a positive one

is

always under-

stood.

further illustration of this very important principle, suppose three wires are fastened together at right angles to one another, and cut off so that their relative lengths

As a

INDICES.

161

shall correspond to the crystallographic axes of sulphur,

a:b:c

0.813

tremities of the a,

1.903 (Fig. 59), then the eight planes joining the exb, and c axes, and another set of eight planes

going from the extremities of the a and b axes to i on the c axis, would have the direction, or make

with one another, the characteristic angles of the faces p and s

(Fig. 60)

which occur on crystals

It

of sulphur.

will be

observed

from a consideration of Figs. 59 and 60 that the faces p, having

their origin at a and b, do not intersect the vertical axis, but, if

extended, would do so at

c.

Also,
FIG. 59.

the faces

having their origin at a certain distance on the vertical

s,

FIG. 60.

axis,

intersect the horizontal axes at points

relative distances, however, at

when extended would beyond a and b. The

which the three axes are cut by the s faces are the same as those of the planes indicated by dotted lines in Fig. 59, going from a b %c, for the s faces are paral:
:

lel to these.

It

must be

distinctly borne in

mind that parameter

relations

furnish a means of expressing the directions of crystal faces when they are referred to axes of known lengths and position,

but they in no way affect the size of the faces. A crystal face may be regarded as shifted to any extent, provided it is kept parallel to its original position, without in the least affecting the
relative distances at Indices.

which the axes are intersected. The position and direction of crystal faces with

reference to axes can also be expressed by numbers, known as The recipindices, which are the reciprocals of the parameters. Inrocal of a number is one divided by the number, 4 = 0.
dices are written as whole numbers, the reciprocal values being

cleared of fractions

when

necessary, and the

minus

sign,

when

needed,

is

written over the number.

162

SYMMETRY.
will serve to illustrate the relations of

The following examples parameters and indices

:

Parameters.

Indices.

Parameters.

Indices.

a b a :b
:

Ill

2a

122
:

coc
:

110
c

a a

f
b
:

1}

3c

321

oca
If

oo&

001

113

one will keep in mind the reciprocal relation existing between indices and parameters it soon becomes an easy matter to use indices, and to conceive of the position and direction of
,

and b The indices 122 (read one, two, two) designate a face intersecting a, %b, and \c such a plane is parallel to, and, thereend of
c.
;

crystal faces expressed plane parallel to the a

by them.

For example, 001 designates a axes, and intersecting the negative

fore, crystallographically identical with, a plane expressed

by the
:

parameter relation 2a
(Fig. 61).

The indices
%b,

321

designate a face intersect-

ing Ja,

and

c,

which

is parallel to

the face hav-

ing the parameter relation

a
FIG. 61. FIG. 62.

-f

ft

3c (Fig. 62).

important to note the order in which the indices are written, the first, second, and
It is

third numbers referring invariably to the characteristic a, c axes.

b,

and

Since indices furnish a very convenient

crystallographic
relations,

method

of expressing

they have been almost universally

adopted by crystallographers.

Symmetry.
there
is

Upon examining crystals it will be observed that a certain regularity in the recurrence of faces and angles
is

designated as symmetry. The symmetry of crystals is expressed in terms of imaginary planes and axes passing through them.
of the

same kind, which

THE CRYSTAL FORM.

163
it

Symmetry Plane.

A plane is

called a

symmetry plane when

manner that the faces and angles on one side of the plane are repeated on the side directly opposite. Thus in Fig. 63 of orthoclase, the shaded plane divides the figure
divides a crystal in such a

symmetrically. A symmetry plane is of such a nature that, if a crystal is held before a mirror with the symmetry plane parallel to the reflecting
surface, the crystal

and

its reflection

present the

same appearance.

Symmetry Axis. When a crystal, on being revolved, shows a recurrence of similar faces and angles, the direction about which the revolution has taken place is called an axis of symmetry.
In Fig. 63 the direction at right angles to the face b is an axis of symmetry by a turning of 180 about this axis, the crystal
;

would occupy the same position in space, and therefore present The symmetry of crystals as referred to the same appearance. axes is of four kinds binary, trigonal, tetragonal, and liexa:

gonal, according as the recurrence of similar parts or features takes place two, three, four, or six times during a revolution of 360, and the four kinds are indicated by the following signs:
Crystallographic axes, (page 159) correspond to axes of sym-

metry whenever it is possible to make them. Center of Symmetry. A crystal is said to have a center of symmetry when it is so developed that for every face there is a
possible one of exactly similar character, diametrically disposed with reference to a central point.

Crystal Form. All of the faces of the same kind which are possible on a crystal of given symmetry constitute a crystal form. For example, take the axes of binary symmetry, a -a,
64), which are of unequal lengths and at one another, and assume that there are three planes of symmetry, each passing through two of the axes the eight faces intercepting the extremities of the axes would then

The

b -b,

and

c -c (Fig.

right angles to

164
be alike

THE CRYSTAL FORM.

and would produce a form known as a pyramid. In giving the symbol of such a form it is customary to give the parameters a b c, or indices (111) of only one of the faces, since the number
: :

same kind can readily be told, provided the symmetry is 'known. In Fig. 63, which represents an orthoclase crystal with one axis of binary symmetry and
of possible faces of the

one plane of symmetry, there are three forms, b, c, and y, each consisting of two faces, and
a fourth
resents the

form m, having four faces. Normal or Holohedral Forms.

Fig. 64 rep-

most symmetrical arrangement of the crystal faces about the axes a -a, b -b, and c -c. Eight faces of the same kind are possible, all of which are developed, and the term normal form will be used for designating crystals of this characcustomary to designate such a form as TioloTiedral (oAo^ whole, and edpa, face). Hemihedrism. About a system of three, unequal axes, at right angles to one another, it is possible to have forms with a lower degree of symmetry than
ter.

It is also

that of the pyramid (Fig. 64). For example, provided the axes are symmetry axes, and that there are no planes of symmetry, the form

would then consist of four faces Such a form is often designated as (Fig. 65). Jiemihedral (?//^, half, and edpa, face), since it has
(111)

a:b:c

only half as

many

faces as are possible

when

symmetry prevails. FIG. 65. Hemimorphism. This term is applied to the property, exhibited by some minerals, of having different crystalline forms at
opposite extremities of an axis of symmetry. Thus, a crystal of calamine (Fig. 66) shows the forms lettered c, t, and i above, which are different from v below. Crystals of tourmaline (Figs. 67 and
68)

the highest degree of

have very different forms at the upper and lower extremities

CKYSTAL HABIT.
of the vertical axis.
electricity, see p. 231.

165

Hemimorpliic crystals show marked pyro-

FIG. 66.

FIG. 67.

every substance that its crystals possess a certain kind of symmetry, or belong to a certain system of crystallization, although their forms or habit may
It is characteristic of

Crystal Habit.

be very

different.

Thus

Figs. 69, 70,

and 71

illustrate the

forms

FIG. 69.

FIG. 70.

FIG. 71.

of the cube, octahedron, and dodecahedron, which

may be

observed

in fluorite.

The shot models

(Fig. 50, p. 156) also

show these three

forms, and will perhaps serve to explain why it is that there can be a difference in habit. The forms of the models depend upon

the directions of the layers of shot which represent the outer or limiting surfaces, while the arrangement of the shot with reference
to one another

on

is the same in all three models. As explained each chemical substance possesses a definite arrangement p. 155, of its crystal molecules, but layers of molecules having different

directions

may

constitute the crystal faces.

It

Distorted

Crystals.

generally happens that during

the

growth

of crystals material is supplied more abundantly to some than to others, and consequently they do not attain an ideally parts

166

CRYSTAL COMBINATIONS.

symmetrical development. For example, although, pyrite crystallizes in cubes (Fig. 72), it is frequently found in forms having some faces larger than others (Figs. 73 and 74). These forms, although
are considered, crysdeparting from the type of a geometrical cube,

i_
FIG. 72.
FIG. 73.

FIG. 74.

tallographically, as distorted cubes, since each interfacial angle equals 90, and all the faces have similar physical properties. a disFig. 75 represents a symmetrical octahedron and Fig. 76,

torted one

Fig. 77, a symmetrically developed quartz crystal, and and 2 Fig. 78, a distorted one with the corresponding faces m, r,
;

differently developed.

FIG. 75.

FIG. 76.

FIG. 77.

FIG. 78.

Distorted crystals are the rule rather than the exception, although the distortion is not usually so great as represented by the foregoing illustrations. Moreover, it should be clearly understood
that the characteristic interfacial angles of crystals are in no affected by inequalities in the size of similar faces.

way
dif-

Crystal Combinations.

The occurrence of two or more

ferent forms, or dissimilar kinds of faces, on a single crystal is called a combination. Fig. 60 (p. 161) illustrates the way the forms

p and s combine on a crystal of

sulphur, and Fig. 63

(p. 163),

a com-

TWIN CRYSTALS.
bination of the four forms
&, c, y,

167

and

m on a crystal of orthoclase.

Farther on, when the systems of crystallization are described, this important subject of crystal combinations will be more fully illustrated

and explained.

Truncations.

When

an edge which would be formed by the

is

meeting of two crystal faces

said to be truncated.

is replaced by a plane, that edge 79 represents a cube a Fig. whose edges are truncated by the planes d. The term truncation is generally used in a restricted

sense, to denote that truncating planes

make equal
the angles
FIG. 79.

angles with the adjacent

faces.

When

on adjacent faces are unequal the term oblique

truncation
is

used.
is

A solid angle
replaced

said to be truncated

when

it is

by a

plane.

Fig. 80 represents a cube a

whose

solid angles are truncated

Twin

Crystals.

When

by the planes o. crystals grow together

FlG 80
-

in other than a

parallel position, so that they have a certain crystallograpTiic plane, or direction, in common, they are known as twin crystals. These generally present the appearance of two halves of a crystal
(Fig.
81)

known

united by a plane called the twinning-plane, and are as contact twins. Twin crystals of this type are of such a

81.

FIG. 82.

FIG. 83.

nature that die lorm of a simple crystal would result if the twins were cut in two along the twinning-plane, and either one of the
halves should be revolved 180 about an axis which
angles to the twinning-plane.
Sucli an axis is
is

at right

known

as the twin-

ning -axis.

For example,

if

the lower half of the twin crystal rep-

168

TWIN CRYSTALS.

resented in Fig. 81 was thus revolved, an octahedron (Fig. 82) would result hence such a crystal is called a twinned octahedron.
;

Two

individuals

may

also appear as penetrating

brought into the same position as the other by a revolution of 180 about the twinningFor example, the cube a if thus revolved about the twinaxis.
is

another (Fig. 83) this type of twins one of the individuals

and such are known

as penetration twins.

through one In

ning-axis

1 1

would assume the position

of the cube a.
is

twinning-plane can never be a symmetry-plane, and

almost

invariably parallel to a face having a simple relation to the crystallographic axes.

Fig. 84 represents a simple crystal of aragonite Fig. 85, a faces is the twinning-plane twin in which one of the and
;

Fig. 86, a repeated twinning, in which the parts I and III are in a parallel position, and have between them a lamella II in twin
position.

When there are a series

is

of lamellae in twin position the

twinning

said to be poly synthetic.

Fig. 87 represents a piece of

*z&
Om

FIG. 84.

FIG. 85.

FIG. 86.

FIG. 87.

where the polysynthetic twinning has given rise to a surface which appears distinctly striated, and consists of a series of alternating re-entrant and salient angles. Fig. 88
oligoclase feldspar

represents a twin grouping of rutile prisms which cross one another at angles of about 60 and 120; and Fig. 89, a repeated

twinning of rutile where eight individuals unite to form a rosette.

Twinning often gives

rise to

very complex forms.

THE SYSTEMS OF CRYSTALLIZATION.

169 of twin crys-

Although re-entrant angles are a prominent feature

tals, they are not to be taken as a necessary indication of twinning. Crystals grow together in parallel and all possible accidental posi-

FlG.

FIG. 89.

FIG. 90.

tions, giving rise occasionally to

which may closely resemble twin from them. Fig. 90 represents a

magnetite.

groupings with re-entrant angles crystals, but are entirely distinct

parallel

growth of octahedrons of
is

The Systems

of Crystallization.

Although there
all

an almost

unlimited variety in the forms of crystals, they can

be classified
:

under the following six

I.

divisions, or systems of crystallization

III.

Isometric.

Hexagonal.

V. MonocKnic.

VI. Triclinic. Tetragonal. The character of the different systems, and the prominent forms which they present, will be described on subsequent pages.
II.

IV. Orthorhombic.

ISOMETRIC SYSTEM.

a3

The forms in

this system

can be referred
-a 2

to three axes, whicJi

are at right angles to

one another and of equal lengths (Fig. 91). Since the axes are alike, they are all designated by the symbol
crystal faces to
a,

but in referring
definite

-a 3
FIG. 91.

adopted, as a, a,
,

them a and a
the

order

is

s.

forms of

Normal Group.

Galena- Type.

by

All the forms and combinations of this group are characterized having three axes of tetragonal, four of trigonal, and six of

170

ISOMETRIC SYSTEM.
also

binary symmetry (Fig. 92)

by having three
94).

axial

and six

diagonal planes of symmetry

(Figs. 93 and

FIG. 92.

FIG. 93.

FIG. 94.

Cube.

The cube a The

(Fig. 95)

has six square faces, each of

parallel to the other two.

which

intersects one axis

is (100).

and

is

The

The faces are all This is also true of the eight solid angles and twelve edges. alike. (Compare distorted cubes, p. 166.) Galena, fluorite, and halite commonly crystallize in cubes. Octahedron. The octahedron o (Fig. 96) has eight faces, each of which intersects the three axes at equal distances from the cenThe symbol is (111). The faces are equilateral triangles and ter. the interfacial angles are 70 32'. The faces are alike, as are also the six solid angles and the twelve edges. (Compare distorted octahedrons, p. 166.) Galena, magnetite, and fluorite often crystalsymbol
interfacial angles are

90.

lize in

octahedrons.

FIG. 95.

FIG. 96.

FIG. 97.

Dodecahedron. The dodecahedron d (Fig. 97) called often the rhombic dodecahedron, has twelve rJiombic faces, each of which intersects two of the axes at the same distance and is parallel to the third. The symbol is (110). The interfacial angles are 60.

The

faces are alike,

and so

also are the twenty-four edges, but the

NORMAL GROUP.
solid angles are of
:

171

two kinds, namely those at the extremities of the axes, made by the meeting of four faces, and those at the centers of the octants, made by the meeting of three faces. Garnet and magnetite occur in dodecahedrons. Crystals which show the combination of the cube a, the octahedron o, and the dodecahedron <#, as illustrated by Figs. 98 to 104, will often be found. None of these combined forms receive a special

name, but can be designated as follows

Fig. 98, a combina-

FIG. 98.

FIG. 99.

FIG. 100.

,.,
(

FIG. 101.

and octahedron Fig. 102, a combination of octahedron and dodecahedron Fig. 104, a combination of cube, dolion of cube
; ;

FIG. 102.

FIG. 103.

FIG. 104.

decahedron, and octahedron, illustrate such combinations.

etc.

Galena, fluorite, and magnetite

The trapezohedron (Fig. 105) has twenty-four similar faces, each of which is a trapezium. Each face intersects one axis at a certain distance (unity) and the
Trapezohedron.
This other two at equal multiples of unity. form has two kinds of edges and three kinds of
solid angles.

symbol
analcite,
(311)

(211) is

trapezohedron having the the common form of garnet,

and

leucite.

One with the symbol

its
FIG. 105.

would

differ

from the one figured in

interfacial angles, although the

arrangement of the faces would

be similar.

172

ISOMETRIC SYSTEM.
Fig. 106 (garnet) represents the trapezohedron

(211) in

com-

bination with the dodecahedron

Fig. 107 (analcite), a combina-

FIG. >06.

FIG. 107.

FIG. 108.

same trapezohedron n with the cube a and Fig. 108 (magnetite), the trapezohedron m (311) with the dodecahedron d. Trisoctahedron. This form has twenty -four triangular faces, each cutting two of the axes at unity and the third at a multiple of unity. The one shown in Fig. 109 has the symbol (221). Fig.
tion of the
;

110 represents a combination of this form hedron o, which occurs in galena

(221)

with the octa-

Tetrahexahedron.

This

form has twenty-four

triangular

FIG. 109.

FIG. 110.

FIG. 111.

FIG. 112.

at unity, a second at a multiple of faces, each cutting one axis The one shown in Fig. Ill has unity, and a third at infinity. the symbol (210). Fig. 112 is a combination of (310) with the

cube

a,

which occurs in

fluorite.

Hexoctahedron.

This form has forty-eight triangular faces.

FIG. 113.

FIG. 114.

FIG. 115.

PYRITOHEDRAL GROUP.

173

each cutting one axis at unity and the other two at different multiples of unity. The one shown in Fig. 113 has the symbol (321 ). Fig. 114 (garnet) represents a combination of this form s (321) with

with the cube

the dodecahedron d, and Fig. 115 (fluorite), the hexoctahedron t (421) a. Such combinations are only occasionally observed.

There are in

all

seven kinds of simple forms in the normal

group

the cube, octahedron, dodecahedron, trapezohedron, trisoctahedron, tetrahexahedron, and hexoctahedron. It is possible
:

may crystallize in any of these forms, there are certain forms and combinations which although usually are especially common in and characteristic of individual species.
Thus galena and
fluorite crystallize usually in
;

that an isometric mineral

cubes and octa-

hedrons, or their combinations magnetite, in octahedrons and or their combinations dodecahedrons, garnet, in dodecahedrons
;

and trapezohedrons

(211), or their combinations

analcite, in trapezohedrons (211).

It is

and leucite and very seldom that galena is

;

found in dodecahedrons, magnetite in cubes, or garnet in either cubes or octahedrons.

ISOMETRIC FORMS OF LOWER SYMMETRY THAN THAT PRESENTED BY THE NORMAL GROUP.
Pyritolieclral Group. Pyrite Type. Crystals of this group are characterized by having three axes of binary and four of trigonal symmetry
(Fig. 116)
;

also three axial planes of sym-

metry

(Fig. 93. p. 170).

Pyritohedron. This form (Fig. 117), sometimes called the pentagonal dodecahedron, has
twelve pentagonal faces, corresponding in position to the alternating faces of the tetraFIG. 116.

hexahedron.

The symbol

of the pyritohedron figured is (210), the

same as that

of the tetrahexahedron (Fig. 111).

Diploid. This form (Fig. 118) has twenty-four faces which correspond in position to half of the faces of the hexoctahedron. The

symbol of the diploid figured hexoctahedron (Fig. 113).

is

(321),

the same as that of the

174

ISOMETRIC SYSTEM.

The

cube, octahedron, dodecahedron, trisoctahedron,

and trap*

ezohedron occur in this group, but they differ from the forms of the normal group in having a lower kind of symmetry. Thus it may generally be observed that the cubes of pyrite are striated,

FIG. 117.

FIG. 118.

FIG. 119.

running in one direction on each cubic face, and at right angles to one another on adjacent faces (Fig. 119). The striations result from the tendency of the cube to crystallize in combination
the
striae

with the pyritohedron (Fig. 117). The crystallographic axes of such striated cubes are axes of binary symmetry, and not of tetragonal symmetry therefore the cubes are not normal ones. Turn
;

a cube of galena about

its vertical

axis and

it

will present the

same appearance four times during a complete revolution, but a striated cube of pyrite similarly turned will present the same
appearance only twice.

FIG. 120.

FIG. 121.

FIG. 122.

FIG. 123.

FIG. 124.

FIG. 125.

FIG. 126.

The combinations

of the cube a (100)

(210)

with the pyritohedron e

and the octahedron o (111) and the diploid t (421), represented

TETRAHEDRAL GROUP.

175

by

Figs. 120 to 125, illustrate forms

cobaltite, all of

which may be observed in

pyrite and

which serve to show the characteristic

Fig. 126 represents a penetration twin

symmetry of this group. of two pyritohedrons.

Tetrahedral Group.

TetraJiedrite Type.

Crystals of this type are characterized by having three axes of binary and four of trigo-

symmetry (Fig. 127), and also six diagonal planes of symmetry (Fig. 94, p. 170). The commonest form is the tetrahedron, from which
nal

the group derives its name. Tetrahedron. This form o

FlQ 127
(

111) (Fig. 128) has

four faces,

corresponding in position to the alternating faces of the octahedron (Fig. 96). The faces are equilateral triangles, and the interfacial angles are alike, 109
28'.

Two

which

differ in position

o (111) (Fig. 128) o

l

tetrahedrons are possible being designated as the

positive tetrahedron

and

(111) (Fig. 129), as

the negative.

The

crystallographic axes join the centers of opposite edges. The positive and negative tetrahedrons may occur in combination, as

represented by Fig. 133.

FIG. 138.

FIG. 129.

Tristetrahedron.

This

form has twelve triangular faces,

corresponding in position to half of the faces of the trapezohedron (Fig. 105). The form
represented by Fig. 130 has the symbol (211). Possible forms in this group, which are occasionally seen in combination with other
18 forms, are the deltoid dodecahedron (Fig. 131) and the Tiexakistetrahedron (Fig. 132), whose faces correspond
-

ISOMETRIC SYSTEM.
to half of those of the trisoctahedron (Fig. 109)

and the hexocta-

hedron

(Fig. 113), respectively.

FIG. 131.

FIG. 132.

The cube a (100), the dodecahedron d (110), and the tetrahexa hedron occur in combination with the foregoing tetrahedral forms,

From

Fig. 127

it

may

be seen that in the cube of this group the

This
is

diagonally opposite solid angles are not alike.

further

shown by the combination of the cube and tetrahedron (Fig. 134). By comparing Figs. 134 and 137 with Figs. 98 and 103, respectively, it will be seen that both the cube and dodecahedron of this group differ from the normal cube and normal dodecahedron of the
galena type.
Tetrahedrite, sphalerite, and bora cite. occur in tetrahedrons and tetrahedral combinations, and Figs. 133 to 138 represent some of

the combinations which

may

be observed, where o

is

the positive

FIG. 133.

FIG. 134.

FIG. 135.

FIG. 136.

FIG. 137.

FIG.

13.

and o, the negative tetrahedron, a the cube, d the dodecahedron, and n the tristetrahedron (211).

TETRAGONAL SYSTEM.

177

TETRAGONAL SYSTEM.
The forms in this system are referred to three axes, all at right angles to one another. The two lateral axes a (Fig. 139) are equal
interchange, while the vertical axis c differs from these in length andin character. The length of the vertical axis has to be determined by the measurement of appropriate angles for each substance crystal-

and

lizing in this system.

ample, c

In zircon, for ex0.640, a being taken as unity.

the

Forms of
The
axis of tetragonal
(Fig. 140)
;

Normal Group.

Zircon Type.

crystals of this

group are characterized by having a vertical symmetry and four axes of binary symmetry

also one horizontal

and four

vertical planes of

sym-

metry

(Fig. 141).

178

TETRAGONAL SYSTEM.

the lengths of their vertical axes are not alike. Fig. 145 represents the pyramid in zircon where c = 0.640 Fig. 143, one of braunite where c = 0.985 (the interfacial angles in this case are near those of
;

the isometric octahedron, Fig. 96)

and Fig.

144,

one of octahedrite

where

= 1.777.

FIG. 142.

FIG. 143.

FIG. 144.

Another form, known as the pyramid of the second order

(Fig.

This form, like that of the pyramid of 145), has the symbol (101). the first order, has eight similar faces which are isosceles triangles,

two kinds
sents the

of edges,

and two kinds of

solid angles.

Fig. 145 repre-

pyramid of the second order of zircon where c = 0.640. On any mineral there may be steeper or flatter pyramids than the unit-forms (111) and (101), according as the faces intercept the
vertical axis at a multiple or fraction of its characteristic length.

FIG. 145.

FIG. 146.

Fig. 146 represents a form known as the ditetragonal pyramid, having eight similar faces above and eight below. Its symbol is 0.640. (311), and the vertical axis corresponds to that of zircon, c

NORMAL GROUP.

179

Prisms. Square prisms are very common and characteristic forms in this group. The form m (110) (Fig. 147) is called a prism of the first order and the form a (100) (Fig. 148) a prism of the sec-

ond

order.

Each

consists of

four similar faces with

(210)

interfacial

angles of exactly 90.

Fig. 149 represents a

form

which has eight similar faces

and

is

known
is

as a ditetragonal prism.

Fig. 150

a plan, or horizontal projection of the lateral axes,

together with the trace of the prism of the first order and the second order a. The necessity for and pyrahaving prisms

mids of two orders

will

become evident when the tetragonal

a 100

combinations are considered.

210

O.

FIG. 147.

FIG. 148.

There

is

nothing in the molecular character of a substance

as the prisms

to determine the length of its prismatic forms,

which occur on a mineral may be either long or short, wholly independent of the characteristic length of the vertical axis c. The pyramidal faces which terminate the prisms have, however, definite inclinations, and from the angles of these the length of the vertical
axis c
is

calculated.

Base or Pinacoid.
Figs. 147 to 149.

The form

c (001) is a

very

consists of two similar parallel faces, the top

common one, and and bottom ones in

The following examples will serve to show the variations in habit resulting from the combinations of tetragonal forms in different minerals. The frequent occurrence of the forms
Combinations.

with

simple

indices
e (101).

is

noticeable

(100), c

(001),

(110),

(111),

and

180

TETRAGONAL SYSTEM.
<?,

The interfacial angles a A a, m A w, a A and ra A c = 90 and a A m = 45. Zircon (Figs. 142 and 151 to 155). Axis <?= 0.640. Angles p Ap = 56 40' and c A ^ = 42 10'. These crystals commonly present the combination of the prism of the
first

order

(110)

with

FIG. 151.

FIG. 152.

FIG. 153.

FIG. 154.

FIG. 155.

the pyramid of the first order p (111). The steep pyramid of the first order u (331) and the ditetragonal pyramid x (311) are occasionally observed.
crystals.

The base

c (001) is

exceeding rare on zircon

Vesumanite (Figs. 156 to 159). Axis c = 0.537. Angles pf\p = 39' and c A p = 37 13'. These crystals usually show the prism of the first order m (110) and of the second order a (100), ter50

FIG. 156.

FIG. 157.

FIG. 158.

FIG. 159.
first

minated either by the basal plane c (001), the pyramid of the order^ (111), or by a combination of both c and#>.
Cassiterite (Figs. 160 to 162).

Axis

58 19' and c /\p

= 0.672. Angles^ Ap =

43

33'.

On

crystals of this mineral the pyra-

mid and prism

of the first order,

(111)

and

m (110), and the prism

of the second order a (100) are the prominent forms. The pyramid of the second order e (101) and the base c (001) occur in com-

NORMAL GROUP.
bination with these.

181

Twin

crystals are

common with

the pyramid

FIG. 160.

FIG. 161.

FIG. 162.

of the second order e (Oil) as twinning-plane. Entile (Figs. 163 to 166). Axis c = 0.644.

Angles
orders,

56 52'

and

Ap=

p Ap =
and

42

20'.

The

crystals are usually prismatic

often capillary.

Prisms of the

first

and second

m (110) and

FIG. 163.

FIG. 164.

FIG. 165.

FIG. 166.

(100), occur and are terminated by the pyramids of the first and second orders, p (111) and e (101). Fig. 164 is a basal projection

of Fig. 163,
of

and shows the symmetrical development of the faces a tetragonal crystal about the vertical axis. Twin crystals of

rutile are very

common, a pyramid of the second order (101) being the twinning-plane. Often a network of prisms, crossing at angles of nearly 60 and 120 (Fig. 165), and zigzag groups (Fig. 166)
Octahedrite (Figs. 1 67 and(168).

result.

Axis c

1 777.
.

Angles p

Ap =

82 9' and c A p = 68 the first order p (111)

18'.

The common form

and

is

the pyramid of

(Fig. 144).

The forms shown

168 are the
first

in Figs. 167

pyramids and second orders, z

fiat

of the
(113)
FIG. 107. FIG. 168.

and x (103), the prism of the first order a (100), and the base c (001).

= 1.251. Angles^ /\p = Apophyllite (Figs. 169 to 172). Axis c 76 0' and c A p = 60 32'. This mineral is characterized by the almost

182

TETRAGONAL SYSTEM.
first

constant occurrence of the pyramid of the

order

(111) in

FIG. 169

FIG. 170.

FIG. 171.

FIG. 172.

combination with the prism of the second order a

plane c (001)
is

(100).

The basal

usually present, and

(310)

is

often prominent (Fig. 172).

The ditetragonal prism y

may

also occasionally be observed.

TETRAGONAL FORMS OF LOWER SYMMETRY THAN THAT PRESENTED BY THE NORMAL GROUP.
Tri-Pyr amidol Group.
Scheelite Type.

This group is characterized by having a vertical axis of tetragonal symmetry and one horizontal plane of symmetry. (Compare Figs. 140 and 141, p. 177).

The characteristics and scapolite.

ScTieelite (Figs.

of the group

may
c

be illustrated by scheelite

173 and
16'.

175).

79 55' and c /\p

= 65

Angles^? A p = Fig. 173 represents a combination of

Axis

1.536.

FIG. 173.

FIG. 174.

FIG. 175.

the pyramid of the first order p (111), of the second order e (101), and a form s having the symbol (131) and known as a pyramid

of the third order.

If the

form

occurred alone

it

would be a

tetragonal pyramid, with its horizontal edges having the directions 3 a a on the lateral axes. pyramid of the third order (133), not
:

SPHEROIDAL GROUP.
so acute as the form
s, is

183

habit with scheelite

is

common represented by Fig. 174. a combination of the pyramids of the first

e (Fig. 175).

and second

orders,

and

0.438. Axis c Scapolite (Figs. 176 to 178). Angles p A p 31 48'. The figures illustrate combinations of 43 45' and c /\p

FIG. 176.

FIG. 177.

FIG. 178.

the prisms of the first and second orders, (110) and a (100), with the pyramid of the first order p (111); while Fig. 178 shows the additional pyramid z (311) of the third order.

should be observed that the forms s (131) of scheelite and z (311) of scapolite are tetragonal pyramids, while the form with
It

corresponding indices in the normal group

is

a ditetragonal pyra-

mid

(Fig. 146).

Sphenoidal Group.
This group
is

Chalcopyrite Type.
vertical axis of binary

characterized

by having a

symmetry and two

two The forms
vertical planes of

horizontal axes

of binary

symmetry

also

symmetry (numbers 4 and

5) (Fig. 141, p. 177).

are illustrated

by

chalcopyrite.

Chalcopyrite (Figs. 179 to 185). Axis c = 0.985. Angles^? A .>,= 70 7%' and c /\p = 54 20'. The form^? (Ill) (Fig. 179) is called a

FIG. 179.

FIG. 180.

FIG. 181.

FIG. 182.

sphenoid.

It has four similar faces, which correspond in their rethe axes to the alternating faces of the tetragonal pyralation to

184

HEXAGONAL SYSTEM.
of the first order (Fig. 143).

mid

analogous to the isometric tetrahedron (Fig. 128), being almost identical with it in its interfacial angles, since the length of the vertical axis of chalcopyrite is so nearly equal to that of the lateral axes. The posiis

The form

and the negative sphenoid p (111) occur in combination (Fig. 180), also twinned (Fig. 181). The acute sphenoid r (Fig. 182) having the symbol (332) and the pyramid of the
tive sphenoid

(111)

second order z (Figs. 183 and 184) having the symbol (201) are
occasionally observed. The twinning-plane of Figs. 181 and 184 is (111). Fig. 185 represents a combination of an acute sphenoid

FIG. 183.

FIG. 184.

FIG. 185.

(772) with a form x (122),

known

as a scalenohedron, but the

are

symbols of these two forms are questionable, because the faces striated and the inclinations therefore not accurately de

termined.

HEXAGONAL SYSTEM.
The forms in
this system are referred to
,

four

axes.

TTic

three lateral axes a n a a

and a

(Fig. 186) are equal

and

inter-

cross at angles of 60 and 120, while the vertical changeable, axis c is of different length and at right angles to them. The length of the vertical axis must be determined by the measurement

and

of appropriate angles for each substance crystallizing in this sysIn beryl, for example, c tem. 0.499, the lateral axes being

taken as unity.
Fig. 187 represents a plan of the lateral axes. In giving the parameters and indices of the forms, the order in which the axes

are taken, a,, a 3 and & s and also the positive and negative directions, as indicated in the figure, should be carefully observed.
, ,

NORMAL GROUP.

185

account of the axial angles of 60 and 120 there are certain relations of the crystal faces to the horizontal axes, represented by
face intersectFig. 188, which should be carefully considered. ing the unit lengths of adjacent axes will be parallel to the third

On

axis

a and indices (101). hence the parameter relation a oo a, face going from unity (a) on one axis to a multiple of unity
; 1
:

rn

(no) on an adjacent axis will intersect the third axis at

^a,

Thus when n = 2, the face may have the parameter relation a and indices (112). When n is a quantity greater than 2a, 2a, 1 and less than 2, for example f the parameter relation may be
: :

fa^

3a a

3,

indices (213).

In every case the third index will be

-a

4Ct 2

-a

-c

FIG. 186.

FIG. 187.

FIG. 188.

equal to the sum of the first and second indices, with the opposite In the complete symbols of hexagonal forms there will be sign. a fourth index, expressing the relation on the vertical axis.

Forms of
The
axis of hexagonal

the

Normal Group.

Beryl Type.

crystals of this

metry (Fig. symmetry (Fig. 190). The forms are of three kinds pyramidal, when the faces intersect the vertical and the horizontal axes prismatic, when the faces are parallel to the vertical axis and pinacoidal, when the
; :

group are characterized by having a vertical symmetry and six horizontal axes of binary symalso one horizontal and six vertical planes of 189)

faces are parallel to the three horizontal axes.

186

HEXAGONAL SYSTEM.

FIG. 189.

FIG. 190.

Pyramids. A form known as the pyramid of the first order The twelve faces, six above and (Fig. 191) has the symbol (1011).
six below, are alike, and are isosceles triangles. The six upper ones have, respectively, the following indices (1011), (Olll), (1101),
:

(1011), (0111), (1101).

A form known as the pyramid of the second

;

order (Fig. 192) has the symbol (ll2) in this the twelve faces are isosceles triangles, the six upper ones having the following
indices: (1122),
(1212),

(2112),

(1122),

(1312),

(2112).

There

may

be

steeper or flatter

pyramids of either

order, according as the

32fi-

FIG. 191.

FIG. 192.

FIG. 193.

vertical axes are

cut at a multiple or a fraction of the unit

length.

Fig. 193 represents a form with twelve similar faces above and twelve below, known as the dihexagonal pyramid. It is only occasionally that a complicated form of this kind is observed in

combinations.

One

is

shown in

Fig. 203 (beryl) lettered n.

(2131),

form represented by Fig. 193 has the symbol

c

The where

= 0.499,

the length of the vertical axis of beryl.

NORMAL GROUP.
Prisms.
:

187

prisms symbol (1010), and the prism of the second or,der, a (Fig. 195), with the symbol (1120). Each kind of prism has six similar faces, with
interfacial angles of

the

Corresponding to the pyramids are two hexagonal prism of the first order, m (Fig. 194), with the

60.

188

HEXAGONAL SYSTEM.
Combinations.

different minerals illustrate

The following representations of crystals of some combinations of hexagonal forms.

In these the prevalence of the forms with simple indices, c (0001),

m (1010), andp (1 Oil) is noticeable. The interfacial angles m A c and a Ac 90, m i\m and a A a = 60, and m A a = 30. Beryl (Figs. 198-203). Axis c = 0.499. Angles p A p = 28 54'
and
c

p=

29

56'.

The common habit

of beryl is a combination

of the prism of the first order,

(1010),

with the base

c (0001).

Crystals showing pyramidal forms of the first order, p (1011), and of the second order, s (1121), and the prism of the second
order,

(1120),

are rather

exceptional.

Fig,

202

is

a basal

FIG. 198.

FIG. 199.

FIG. 200.

FIG. 201.

FIG. 202.

FIG. 203.

projection of Fig. 201, illustrating the development of similar faces in sets of six about the vertical axis. Fig. 203 represents a

highly modified crystal, with the prism m, terminated by a dihexagonal pyramid n (3141), two pyramids of the second order, s and

(3364),

the pyramid of the first order p, and the base c. Axis c 0.870. Pyrrliotite (Figs. 204 and 205).
41
30'

Angles

p Ap =

and

Ap

= 45

8'.

The

crystals of this mineral are

usually tabular, owing to the prominence of the base c (0001), and

PYRAMIDAL GROUP.

189
(101 0),

show the forms

pyramids of the

of the
first

prism of the first order m order, p (1011) and u (4041).

and two

FIG. 204.

Hanksite

(Fig. 206).

Axis

= 1.014.
30'.

Angles

and

Ap

= 49

The common

/\p = 44 41' combination is

that of the prism and pyramid of the first order, (1010) and p (1011), with the basal plane

m
FIG. 206.

c (0001).

HEXAGONAL FORMS OF LOWER SYMMETRY THAN THAT PRESENTED BY THE NORMAL TYPE.
Tri-Pyramidal Group.
This group
is

Apatite Type.
vertical axis of hex-

characterized

by having a

agonal symmetry and one horizontal plane of symmetry.

pare Figs. 189 and 190.)

(Com-

The characteristics and vanadinite.

of the

group

may
Axis

be illustrated by apatite
c

Apatite (Figs. 207, 209 and 210).

0.735.

Angles p A p

44' and c Fig. 207 represents a somewhat com(1010) plex crystal, with the prisms of the first and second orders, and a (1120), terminated by the base c (0001), three pyramids of
18'.

= 37

A p = 40

the

first order,

(2021),

(1011),

and r

(1012),

a pyramid of the

FIG. 207.

FIG. 208.

second order

s (1121),

and a hexagonal pyramid

//

(2131),

known

as a pyramid of the tliird order.

190

HEXAGONAL SYSTEM.

A pyramid of the third order having the symbol

so acute as the form
/*,

(1233),

but not

be represented by observed that the horizontal axes do not join the opposite solid angles, as in the pyramid of the first order (Fig. 191), nor the
is

Fig. 208.

It will

centers of opposite edges, as in the

(Fig. 192).

The

simple crystals of apatite

observed (Figs. 209 and 210) the normal group, but their peculiar symmetry can be revealed by etching with acid, as explained beyond under quartz (page 198).

pyramid of the second order which are ordinarily do not appear to differ from forms of

FIG. 209.

FIG. 210.

FIG. 211.

Vanadinite

(Fig. 211).

Axis

= 0.712.

The

figure illustrates

a rather simple combination of a prism of the first order m (1010) and base c (0001), with a pyramid of the third order ^ (2131).
It should be observed that the form /* (2131) in this group is a hexagonal pyramid, while in the normal group a form with

corresponding indices

is

a dihexagonal pyramid (Fig. 193).

HemimorpMc Group.
This group
is

lodyrite Type.
vertical axis of hex-

characterized

by having a

The agonal symmetry and six vertical planes of symmetry. of the crystals is the development of different forms at peculiarity
opposite extremities of the vertical axis, as illustrated by Fig. 212 of the rare mineral iodyrite, and Fig. 213 of zincite. The pyramids
of iodyrite are

(4041)

and n

(4043).

RHOMBOHEDRAL GROUP.

191

FIG. 212.

FIG. 213.

RHOMBOHEDKAL FORMS OF THE HEXAGONAL SYSTEM.

In crystals of this class the forms are referred to the hexagonal system of axes (Fig. 186), but the vertical axis c is one of trigonal

and not
system.

of hexagonal

lize in this class,

symmetry. Many common minerals crystalwhich is often designated as the rhomboTiedral

Forms

of the

Normal Khomboliedral Group.

Calcite Type.

group are characterized by having a vertical axis of trigonal symmetry and three horizontal axes of binary sym-

The forms

of this

FIG. 214.

FIG. 215.
;

FIG. 216.

metry
metry,

(Fig. 214)
4, 5,

also

by

having three vertical planes of sym(Fig. 215) is characterized

and

6 (Fig. 190, p. 186).

Rhombohedrons.

A rhombohedron

by having

six similar faces which are rhombs and correspond in

their axial relations to the alternating faces of the hexagonal pyramid of the first order (Fig. 191). Rhombohedrons are designated

as positive (Fig. 215)

negative (Fig. 216)

when a face above is toward the observer, and when an edge above is toward the observer.

192

HEXAGONAL SYSTEM.
the faces intercept the vertical axis at unity, the symbols

When

of these forms are, respectively, (1011)

and

(0111).

Furthermore,

rhombohedrons are called obtuse or flat when the solid angles at the extremities of the vertical axis are obtuse, and acute or steep

when these solid angles are acute. Fig. 218 represents an obtuse, and Fig. 221, an acute rhombohedron of calcite. They also have
two kinds of solid angles those at the extremities of the vertical axis, where the plane angles of the faces are alike, and six others in which the plane angles of the faces are of two kinds, either two acute and one obtuse (Fig. 218), or two obtuse and one acute (Fig. The edges are of two kinds, six (three above and three be221).
;

low) running to the extremities of the vertical axis, and six going zigzag around the crystal.

Scalenohedron.

This

is

a form (Fig. 217) having twelve similar

faces, six above and six below, corresponding in position to the alternating pairs of faces of the

dihexagonal pyramid (Fig. 193). The faces are scalene triangles, hence the name scalenohedron.

The edges which meet at the extremities of the vertical axis are of two kinds, long and short, alternately disposed; while the six middle edges are alike, and run zigzag around the crystal, as in the

rhombohedron (Fig. 215). Fig. 217 represents the scalenohedron (2131) which commonly occurs on calcite.

Y FlG 217

Pyramids of the second orders (Fig. 192), prisms m and a of the first and second orders (Figs. 194 and 195), the dihexagonal prism (Fig. 197), and the basal plane c (0001) occur in combination with rhombohedrons and scalenohedrons. The basal plane c when it truncates the top of a rhombohedron is an
Combinations.
equilateral triangle (Fig. 223). Calcite (Figs. -218 to 233).
55'

Axis

= 0.854.

Angles r A r

= 74

and

= 44

36^'.

of habits than almost any other.

This mineral presents a greater variety Of the rhombohedral type the

(0221) and the positive negative rhombohedrons e (0112) and the commonest. The angles of the negrhombohedron r (1011) are

RHOMBOHEDRAL GROUP.
ative
it

193

rhombohedron
without

7i

(0332) are 91

42';

lience this form,

when
cube.

occurs

modifications,

closely

resembles

FIG. 218.

FIG. 219.

FIG. 220.

FIG. 221.

FIG. 222.

FIG.

226.

194

HEXAGONAL SYSTEM.

being either long or short and usually of the first order, (1010). The prisms are terminated by the base c, by rhombohedrons, most often e (Fig. 226), and by scalenohedrons (Figs. 232 and 233).

The scalenohedron most often observed is v (2131) (Figs. 229 to The twinning-plane of Fig. 227 is r (0111), and the vertical 233).
axes are inclined nearly 90 to one another. Fig. 230 scalenohedron with the base as the twinning-plane.
is

a twinned

Corundum (Figs. 234 to 93 56' and c A r 57 34'.

236).

Angles r A r = Crystals of this mineral usually show

Axis

= 1.363.

FIG. 234.

FIG. 235.

FIG. 236.

the prism and pyramid of the second order, a (1120) and n (2243), in combination with the base c (0001) and rhombohedron r (1011).

Hematite
94
0'

(Figs. 237 to 241).

Axis

= 1.366.

Angles r A r

The rhombohedron r (1011) (Fig. 237) occasionally occurs without modification and resembles a cube, since its angles are near 90. Crystals usually show combinations of the
and
c

A r

57

37'.

FIG. 237.

FIG. 238.

FIG. 239.

FIG. 240.

FIG. 241.

rhombohedron r with the base

and a pyramid of the second

order,

(2243).

Very
flat

flat

crystals (scales) are

(1014) or

common with
x
(0.1.1.12)

the basal

plane c or

rhombohedrons u

prominent.

RHOMBOHEDRAL GROUP.
Chabazite (Figs. 242 and
85
14'.

195

243).
is

Axis

= 1.086.

Angles r A r

The common form

closely resembles a cube.

the rhombohedron r (1011), which Fig. 242 represents this form in com-

bination with the negative rhombohedrons e (0112) and./ (0221).

FIG. 242.

FIG. 243.

Fig. 243
cal

a basal projection of Fig. 242 and shows the symmetridevelopment of the rhombohedral faces r, e, and/* about the
is

vertical axis.

RHOMBOHEDRAL FOEMS OF LOWER SYMMETRY THAN THAT PRESENTED BY THE NORMAL TYPE.

HemimorpMc
The
crystals of this

Group.

Tourmaline Type.

axis of trigonal

group are characterized by having a vertical symmetry and three vertical planes of symmetry.

It is characteristic of crystals of this

group that the faces at

opposite extremities of the vertical axis are not alike. The forms 0.448. occur on tourmaline (Figs. 244 to 247). Axis c Angles

A r = 46

62'

and

27

20'.

The. crystals of this mineral

FIG. 244.

FIG. 245.

FIG. 246.

FIG. 247.

(1010) usually present the combination of the triangular prism and the hexagonal prism of the second order a (11^0), which are

terminated above by the forms r

(1011), o (0221),

and occasionally

(3251),

and below by

r (Olli), o (2021), and c (0001).

196

HEXAGONAL SYSTEM.

TrirTiomboJiedral Group.

Phenacite Type.

group are characterized by having a vertical axis of trigonal symmetry and a center of symmetry, but no planes of symmetry.
crystals of this

The

The forms which are especially characteristic are hexagonal prisms, usually a (1150), and rhombohedrons of the first, second, and third orders. The three kinds of rhombohedrons correspond
in their axial relations to one half of the faces of the hexagonal pyramids of the first and second orders (Figs. 191 and 192), and to

one quarter of the faces of the dihexagonal pyramid (Fig. 193). Phenacite (Fig. 248). Axis c = 0.661. The figure represents a prism of the second order a (1130), in combination with a rhombo-

hedron of the third order x

(2132;.

FIG. 248.

FIG. 349.

Here the prism of the Willemite (Fig. 249). Axis c 0.677. second order a is in combination with two rhombohedrons of the
first order,

r (1011) and e (0112), and a

rhombohedron

of the second

order

(2113).

Dioptase (Figs. 250 and 251). Axis c = 0.534. The figures represent combinations of the prism of the second order a, with a

FIG. 250.

FIG. 251.

FIG. 252.

rhombohedron of the

first

order s (02S1), and of the third order

(1341).

TRAPEZOHEDRAL GROUP

197

Ilmenite (Fig. 252). Axis c = 1.385. The figure presents a combination of a rhombohedron of the first order r (1011), and

one of the second order n

(2243),

with the base

c (0001).

Trapezohedral Group.

Quartz Type.

The crystals

of this group are characterized

by having a vertical

axis of trigonal

of binary but no planes of symmetry. symmetry (Fig. 214), Quartz (Figs. 253 to 264). Axis c = 1.100. Angles r A r = The forms which 85 46', r A z = 46 16' and r A m = 38 13'.
first

symmetry and three horizontal axes

(1010), and the and negative rhombohedrons, r (1011) and z (0111), often positive with the two last forms about equally developed (Figs. 253 and An unequal development of these rhombohedrons (Fig. 254). 255) is also common. Although not indicated by their simple

generally occur are the prism of the

order

FIG. 253.

FIG. 254.

FIG. 255.

FIG. 256.

FIG. 257.

combinations,

symmetry.

quartz crystals have a peculiar right or left This is shown by the development of the form

x (5161), on the

right-handed crystal (Fig. 256), and x (6151) on the left-handed crystal (Fig. 257). The form which the six x faces of

one of these crystals would produce

is

known

as a trapezohedron.

Its faces correspond in their axial relation to

one quarter of the faces

The right- and leftof the dihexagonal pyramid (Fig. 193). handed trapezohedrons having the symbols (2131) and (3151) are shown by Figs. 258 and 259. These forms, like the right and left
hand, are symmetrical with reference to a plane passed between them, but cannot by any turning be made to occupy the same In this group the form s (1121) (Fig. 256) develops as position.
.

a triangular pyramid

(Fig. 260),

and has the same symbol as a

198

HEXAGONAL SYSTEM.

pyramid of the second order of the normal group (Fig. 192). Pos itive and negative acute rhombohedrons, (3031) and (0331) (Figs. 261 and 262), often occur. Twin crystals are very common, and are of a peculiar character.

FIG. 258.

FIG. 259.

FIG. 260.

The twinning-plane is usually the prism of the first order m, so that the positive rhombohedron r of the crystal in the normal position coincides with the negative rhombohedron z of the crystal in the twinned position. The parts of the individual in the normal and twin position interpenetrate in a very irregular manner (Fig. 262), and the twin character of the crystal is not usually revealed

by

Often, however, the faces of either the positive or negative rhombohedrons are somewhat corroded (etched) (Fig. 262), and then the irregular lines of penetration between the
its

external form.

r and z and the

M and M

faces can be distinctly traced.

FIG. 261.

FIG. 262.

FIG. 263.

FIG. 264.

Judging from the outward form alone, quartz crystals like 253 and 254 would appear to have the same symmetry as crystals

ORTHORHOMBIC SYSTEM.

199

of the normal hexagonal type. This, however, is not the case, for if quartz crystals are subjected to the action of hydrofluoric acid
artificial faces (corrosion or

etching faces) are developed, which

264), corre-

have a right- or left-handed distribution (Figs. 263 and sponding to that of the x faces on Figs. 256 and 257.

OKTHORHOMBIC SYSTEM.
In tMs system
the

forms are referred

to three

axes

a, b,

and c

at rigJit angles to one another and of unequal lengths (Fig. 265). Any one of these may be chosen for the vertical axes c the
;

longer of the horizontal ones is then taken as b and is called the macro-axis; the shorter, as a and is called the br achy -axis.

For each substance crystallizing in the system the ratio lengths of the axes must be determined from the measurement of appropriate In sulphur, for example, the axial ratio is a b c = angles.
:

0.813

1.903 (see p. 159).

-c'

FIG. 265.

FIG. 266.

FIG. 267.

Forms of
The

the

Normal Group.

Bar lie

Type.

group are characterized by having three axes of binary symmetry (Fig. 266) and three axial planes of symcrystals of this

metry (Fig. 267). The forms are

of three kinds, as follows pyramidal, when tne faces intersect the three axes prismatic, when the faces
: ;

200
intersect

OKTHORHOMBIC SYSTEM.

two axes and are

when the
two.

parallel to the third and pinacoidal, faces intersect one axis and are parallel to the other
;

Pyramids. These consist of eight similar faces, and the form with the simplest symbol, p (111) (Fig. 268), is called
the unit pyramid.

(111)

is

shown

in

In sulphur (Fig. 281) the form combination with a flatter

Thus it will be noticed that on pyramid s (113). the same crystal there may be different pyramids, but under no condition can there be more than eight faces of the same kind.
These consist of four similar faces, parallel to an' axis; three kinds being possible, according as the faces are parallel to the c, the b, or the a axes.
Prisms.
FIG. 268.

Fro. 269.

FIG. 270.

FIG. 271.

Vertical Prisms.

A prominent prism on a crystal is commonly

form

which is known as the unit prism (Fig. 269). This form is a right rhombic prism, its four faces being at right angles to the terminal face c, but never at right angles to one another, since the a and b axes are not of

assumed

to be the

(110),

equal length. Besides the unit prism, others may occur whose faces have such inclinations that they go from a to a multiple of b, or from b
to a multiple of a,

and are

parallel to

c.

One of these is illustrated

by topaz

(Figs. 289 to 293), in which I is the prism (120). Horizontal Prisms, or Domes. When the prismatic forms are parallel to the horizontal axes they are conveniently designated as domes. Fig. 270 represents the form (101), known as

COMBINATIONS,

201

the macro-dome, because

it is

parallel to tlie macro-axis b

and

Fig. 271, the form (Oil), called the br achy-dome, because it is Each of the ^macro- and brachyparallel to the brachy-axis a.

domes has four similar faces. Domes are common forms which, on crystals illustrating combinations in this system, will often appear at one of the extremities as a pair of similar faces. For example, the two triangular faces r at the- extremity of Fig. 298 are planes of the macro-dome (101). In, many instances the domes
intercept the vertical axis at a multiple, or fraction, of its unit length, as illustrated by topaz (Figs. 290 to 293), in which the

brachy-domes/and y have the symbols

Pinacoids.

(021)

and

(041) respectively.

Three pinacoids are possible, each consisting cf two, similar, parallel faces. These forms, represented in Fig. 272, are the macro-

pinacoid a

(100), the brachy-pinacoid b (010), and base or basal pinacoid c (001). The faces of the these three forms are at right angles to one another.

-*#
100

010

Combinations.
result

Thje

following

illustrate the great variety of habits

examples will which may

FIG. 272.

from the combinations of pinacoids, prisms, domes, and

pyramids. It should be noticed that the forms with simple indices,

a (100), b (010), c (001), The position in which the

(110),

and

(111),

are prominent.

crystals are placed (the crystallographic orientation) is to a certain extent arbitrary, since any one of the axes of symmetry may be taken for the vertical axis c.

Barite (Figs. 273 to 277).

Axes a

= 0.815

1.314.

An.

FIG. 276.

FIG. 277.

gles m A m

78 22' and c
c

A = 52
o

43'.

The

crystals

have the basal plane

prominent and

are, therefore, tabular.

commonly The

202

ORTHORHOMBIC SYSTEM.

prism

(110),

the macro-dome d (102), and the brachy-dome o

(Oil) are generally present.

Celestite (Figs. 278

Angles

m A m = 75
o (Oil)

tabular like Figs. lengthened out in the direction

and 279). Axes a b c = 0.779 1 1.280. 52 0'. The crystals are often 50' and c A o 273 to 275 of barite, and often they are
: : :
:

of

brachy-axis,

having

the

brachy-dome

prominent (Fig.

279).

The prism

(110)

and

FIG. 278.

FIG. 279.

the macro-dome

(102) are generally present, while

(104) occurs

occasionally (Fig. 278).

FIG. 280.

FIG. 281.

FIG. 282.

Sulphur
Angles
is

mf\m

Axes a b (Figs. 280 to 282). 62 17'. 78 14' and c/\n

:

0.813

1.903.

pyramidal habit,

p (111), common, often with the apex truncated by the pyramid The brachy-dome n (Oil) is also often s (113) or the base c.
present. Stibnite (Figs. 283 and284).

Axes a :b :c

= 0.992

1.018.

Angles

mAm^8934

prismatic, with the prism

55 19'. The crystals are and c/\p m (110) and the brachy-pinacoid b (010)

COMBINATIONS.

203

prominent. They are often long and slender, and are generally terminated by the pyramidal forms p (111), s (113), and r (343).

FIG. 283.

FIG. 284.

Arsenopyrite(F\g&. 285 and286). Angles m A m = 68 13' and cA q

Axes a
49

b c
:

= 0.677

1 .188.

55'.

short prism
is

(110), terminated by the brachy-dome u (014), is the The brachy-dome q (Oil) terminating the prism habit.

common
occa-

sionally

met

with.

FIG. 285.

FIG. 286.
: :

and 288). Axes a b :c = 0.582 1 0.970. = 60 25' and c A d = 62 44 The crystals are comAngles ml\m monly flat, with a striated basal plane c (001) and the brachy-dome
CTialcoclte (Figs. 287
:

FIG. 287.

FIG. 288.

(021)

v (112),

prominent. The prism (110), two pyramids^? (HI) and and the brachy-pinacoid b (010) are common forms. Twin

204

ORTHORHOMBIC SYSTEM.

crystals are very

common, and frequently imitate forms

: :

of the

hexagonal system, as will be explained under aragonite (p. 206). Axes a b c 0.528 1 0.477. Topaz (Figs. 289 to 293).

Angles m

55 43' and c f\p

= 45

35'.

The

crystals are gen-

erally prismatic, with two prisms developed,

(110)

and

Z(120).

FIG. 289.

FIG. 290.

FIG. 291.

FIG. 292.

FIG. 293.
l

The forms which usually occur at the terminations are the base c the brachy-domes / (021) and y (041), the macro-dome d (201), and the pyramids o (221), p (111), and i (223). Doubly terminated
,

rystals are rather exceptional.

Chrysolite (Figs. 294 to 296). f\m 49 57' and c A p Angles

Axes a
54
15'.

0.466

0.586.

In the vertical zone

FIG. 294.

FIG. 295.

FIG. 296.

the pinacoids a (100) and b (010) and the prism present, and occasionally, also, a second prism s

m (110) are usually

(120).

The

crystals

COMBINATIONS.
are terminated

205

by the brachy-dome 7c

(021),

the macro-dome

d (101),

the pyramid p (III), and occasionally, the basal plane c (001). Fig. 296 is a basal projection of Fig. 295, which shows the symmetrical development of the orthorhombic forms when viewed in the direction of the vertical axis.
0.473 1 0.683. Staurolite (Figs. 297 to 300). Axes a b c A in 50 40'. The crystals are generally prismatic, with Angle
: : :
:

the prism

(110)

and the brachy-pinacoid

(010)

developed.

\)tl

FIG. 297.

FIG. 298.

FIG. 299.

FIG. 300.

They
of c

are terminated either

by the base

c (001), or a combination,

Penetration twins are very common; the prisms crossing either at nearly 90 when a brachy-dome (032) is the twinning-plane, or at nearly 60 when a pyramid (332)

and the macro-dome r

(101).

is

the twinning-plane. Aragonite (Figs. 301 to 307). = 63 48' and c A k A Angles

Axes a

= 0.662

0.721.

m m

= 35

4T.

Slender, needle-like

\
FIG. 301.

\
FIG. 303. FIG. 304.

FIG. 302.

crystals, either tapering to

(usually the brachy-dome

~k

a point or with well-defined faces (Oil) ) at the extremity, are common

206
(Fig. 301).

ORTHORHOMBIC SYSTEM.

The indices

of the steep

pyramid i (661) and the brachy-

dome j

(0.12.1)

are uncertain.

Simple crystals (Fig. 302) show,

ing the combination of the prism m, the brachy-pinacoid while twins (Fig. the brachy-dome ~k are exceptional
;

and
303),

more often observed, the prism A complex method of twinning m and intergrowth is common, from which a form resembling a hexagonal prism results. The character of these apparently hexagonal The cross-section of a simcrystals may be explained as follows
often polys ynthetic (Fig. 304), are (110) being the twinning-plane.
:

ple crystal like Fig. 302 is represented

by

Fig. 305.

Three indi-

^X^' ms^^m

ilj
^^^^

FIG. 305.

FIG. 306.

FIG. 307.

viduals
axis,

I, II,

and

III (Fig. 306), each striated parallel to the brachy-

and

crystallizing with their prismatic faces

as the twin-

ning-planes, would diverge

at angles of about 120.

Provided

that each crystal penetrated beyond the center, a six-sided form would result, with the individuals meeting along the somewhat
irregular lines of interpenetration (Fig. 307).
ter of

The complex characon the basal

such twins

is

generally revealed

by

striations

planes, diverging as represented in Fig. 307,

and

also

by small

re-

entrant angles.

There

is

a tendency in a number of minerals having a, prismatic angle of nearly 60, to occur in complex twin crystals like those of aragonite,

which imitate forms of

the hexagonal system. Cerussite (Fig. 308).

Angle m A m = 62 a form with deep re-entrant

FIG. 308.

Axes a c=0.610 1 0.723. 46'. The figure represents

:

t>

angles, resulting

from

tion.

the penetration of three individuals in twin posi(Compare Figs. 306 and 307 of aragonite.) Each crys-

SPHEROIDAL GROUP.
tal

sor

has the brachy-pinacoid b (010) prominent, in combination with the prism Occasion(110) and the pyramid p (111).

ally twin crystals of cerussite occur without the re-

entrant angles, when they may appear like a combination of the pyramid and prism of the hexagonal

system.
Cliildrenite (Fig. 309).

Axes a\l\c

= 0.778

0.526.

This example has been introduced to illustrate the combination of a pyramid FIG. s (121) in combination with the pinacoids a (100) and & (010).

Angle

mAm

75

46'.

309.

ORTHORHOMBIC FORMS OF LOWER SYMMETRY THAN" THAT PRESENTED BY THE NORMAL GROUP.
HemimorpJiic Group.

Calamine Type.

group are characterized by having one axis of binary symmetry and two planes of symmetry. The of the crystals is that the forms at oppopeculiarity
site

The

crystals of this

extremities of the axis of

symmetry
:
:

are

not

alike.

Calamine (Fig. 310).

Angle
FIG. 310.

mA m=

76

9'.

Axes a c = 0.783 The combination

: t>

0.478.

of
~b

the
(010),

macro-pinacoid a and the prism m

(100), the brachy-pinacoid (110), is terminated above

i (031)

by the
t (301),

base c (001) and the brachy- and macro-domes while below the pyramid v (121) occurs.

and

Sphenoidal Group.

Up somite

Type.

/V__?./ \

Crystals of this group are characterized by having three axes of binary symmetry and no planes of

symmetry. Epsomite (Fig.

311).
26'.

Angle

mAm=

89

FIG. Axes a b c=0.990 1 0.571. The figure represents the prism m

: :

311.

(110),

208

MONOCLINIC SYSTEM.
z,

terminated above and below by two faces of the form

having

the symbol (111). The four z faces alone produce a form known The faces correspond as a sphenoid, similar to Fig. 65, p. 164.

rhombic pyramid

in their axial relations to the alternating planes of the ortho(111) of the normal group.

MOJSTOCLINIC SYSTEM.

In this system the forms are referred to three axes, a, b and c of unequal lengths, with a and c intersecting at an acute angle The fi behind, while b is at right angles to a and c (Fig. 312).
axis b
is called
;

the other two

the ortho-axis, because it is at right angles to and a is called the clino-axis, because it is inc.

clined to the vertical axis

For each substance crystallizing in and the axial inclination ft must be determined from the measurement of appropriate angles. For gypsum the axial relation is a b c = 0.690 1 0.412
this system the ratio lengths of the axes
:

= 80 fi
The

42'.

Forms of the Normal Group.

crystals of this

Gypsum

Type.

of binary symmetry (Fig.

tallographic axis
b,

group are characterized by having one axis 313), which is always taken as the crysof

and one plane

symmetry.

The plane

of

FIG. 312.

FIG. 313.

FIG. 314.

symmetry
tion,

(Fig. 314) is

always supposed to occupy a vertical posiit.

and the a and

c axes are located in

;

Monoclinic forms are of two kinds

similar faces, or pinacoidal with

either prismatic with four

parallel faces.
It is con-

two

NORMAL GROUP.

209

venient, however, to designate the forms according to their relation on the axes as pyramids, when the faces intersect all three
:

axes

prisms

or domes,
;

parallel to one

when they intersect two axes and are and pinacoids, when they intersect one axis and

are parallel to the other two.

Pyramids. The form (111) (Fig. 315) consists of four similar faces. These four faces really constitute a prism with its edges parallel to the direction a c. The name pyramid is simply one of
:

convenience for designating the particular kind of form which intersects the three axes. A somewhat similar, but different, and entirely

independent form

is (111)

(Fig. 316), also consisting of four

FIG. 315.

FIG. 316.

FIG. 317.

similar faces.

The

solid represented

by

Fig. 317 is a combination

of the two independent forms p (111) and o (111). It should be distinctly understood that no form in this system is more complicated than the ones just explained. The symbol may be less simple,

example (321), but the symmetry demands the existence of only four faces of the same kind.
for

Prisms.
is

commonly

prismatic form, consisting of four similar faces Such a taken as the unit-prism (110) (Fig. 318),

FIG. 318.

FIG. 319.

FIG. 320.

an inclined prism, the two faces in front making equal with the terminal face c, but not angles of 90. Besides angles form
is

210

MONOCLINIC SYSTEM.

the prism (110) others occur, whose faces are so inclined that they go from a to a multiple of &, or from b to a multiple of a, and are parallel to c. Two prisms, (110) and z (130), often occur on

orthoclase (Fig. 328).

Domes.

The form

(Oil) (Fig.

319) has

four similar faces

which make an inclined prism.

parallel to the clino-axis a.

It is

convenient to designate this

form, however, as a clino-dome, so named because the faces are

to the of monoclinic crystals the form (101)
Fig. 320 represents

Owing

symmetry
and
b.

occurs as a pair of similar faces.

two inde-

pendent forms
Pinacoids.

(101)

(101), called ortho-domes, in combination

with a terminal face

There are three forms, each

consisting of

two

parallel faces (Fig. 321), which are especially important the ortTio-pinacoid a (100), the clino:

pinacoid
c (001).

and the base or basal pinacoid The clino-pinacoid &, which is parallel to
b (010),

FIG. 321.

the symmetry plane (Fig. 313), is at right angles to both the base c and the ortho-pinacoid a, while the two latter forms make an angle with
is

one another which

equal to the axial inclination

fi.

The following examples will illustrate some of which may result from the combination of monthe various habits oclinic forms, and it should be noticed that it is possible in almost
Combinations.
all cases, to orientate

the crystals so that- the symbols of their*

forms can be expressed by very simple indices. forms are the pinacoids a (100), b (010), and c

The prevailing
(001),

the prism

(110),

and the pyramid^

42'.

(111).
:

Gypsum
$ = 80

Axes a b c = 0.690 1 0.412 (Figs. 322 to 325). = 68 30' and^ A p = 36 12'. Crystals A Angles
: :
:

usually have the clino-pinacoid b (010) prominent, in combination The ortho-dome with the prism (110) and the pyramid p (111).

e (103) is

often present. Twins are common, with the ortho-pinacoid (100) as the twinning-plane (Fig. 325).

The arbitrary method

of orientating a monoclinic crystal

and

NORMAL GROUP.

211

naming the forms is here brought to notice. The four faces of the so-called pyramid p, if placed vertically, could have been taken as the prism (110), when the m faces would most naturally be taken
as the clino-dome (Oil).

crystal of

gypsum thus

orientated

\E/
FIG
323.

\y
FIG. 323.

FIG. 324.

FIG. 325.

would, of course, have a different axial ratio than the one given above. The only form on monoclinic crystals which is actually

determined by the symmetry

ft

is

the clino-pinacoid b (010).

OrtJioclase (Figs. 826 to 329).

Axes
13', c

a:b:c=
A x

0.658
16',

0.555

63

57'.

Angles m A m =

61

= 50

80

18'.

The prominent forms

are the prism

m (110)

and c A y = and the pina-

FIG. 326.

FIG. 327.

FIG. 328.

FIG. 329.

coids b (010) and c (001).

A second prism z .(130), the ortho-domes

A (101) and y (201), and the pyramid o (111), are often present. common kind of twinning consists of two individuals united with their b faces in common (Fig. 329). The twinning- axis is the vertical axis c. On the crystal in the normal position the base c toward the front, while in the twinned individual it slopes slopes
toward the back.

Pyroxene
ft

74

10'.

330 to 336). 92 A Angles

(Figs.

Axes a:b:c=
50',

1.092
29',

0.589

m=

p Ap =

48

and

212

MONOCLINIC SYSTEM.
11'.

Prismatic crystals are common, the prisms (110) being = 92 50'), and generally truncated stout, nearly rectangular (m A by the ortho-pinacoid a (100) and the clino-pinacoid b (010). The
59

crystals are variously termipated

base c

(001),

the ortho-domes

the prevailing forms being the (101) and n (102), and the pyramids
;

FIG. 330.

FIG. 331.

FIG. 332.

FIG. 333.

p'(lll), v (221), s (111),

and o

(221).

Fig. 334

is

a basal projection

of Fig. 333,
clinic

and shows the symmetrical development of the monoforms on either side of the symmetry plane, intersecting the

FIG. 334.

FIG. 335.
b.

FIG. 336.

crystal parallel to the face

Figs. 335

and 336 represent the

or-

dinary development of crystals of augite, a variety of pyroxene

common
fi

in volcanic rocks.
(Figs. 337 to 339).

Amphibole

= 73

58'.

Angles m A m =

Axes a I 55 49' and r A r

:

= 0.551
31
32'.

0.294

The

crys-

tals are

nent,

commonly long and bladed, with the prism m (110) promior apparently hexagonal (m A m = nearly 60), when m and

the clino-pinacoid b are about equally developed. second prism e (130) and the ortho-pinacoid a (100) are often present. The are generally terminated by the faces of the clino-dome crystals
r (Oil).

NORMAL GROUP.

213

FIG. 337.

FIG. 338.

FIG. 339.

0.755

Titanite or SpTiene (Figs. 340 1 0. 854 ft = 60 17'. Angles

: :

to

342).

m A m = 66
(110)

andc A p

= 38

16'.

The prism

and

b c = = 43 49', 29', p A p the pyramid p (111)

Axes a

FIG. 340.

FIG. 341.

FIG. 342.

are generally prominent, and in combination with the base c (001)

and the ortho-pinacoid a

ing a wedge,
is

(100).

The very obtuse

interfacial angles

of Fig. 341 are conspicuous, from which the name sphene, meanderived.
344).

Epidote (Figs 343 and

= ft

64

37'.

Angles m

m=

Axes a b c = 1.578 1 1.804 ; 109 66', n A n = 70 29', and c A r =

: : :
:

/-..
FIG. 343.

/
FIG. 344.

crystals of epidote generally have a somewhat unusual development, being long in the direction of the symmetry,

63

42'.

The

axis,

owing to the prominence

of the base c (001), the ortho-pina-

214

TBICLINIC SYSTEM.
i (102).

coid a (100), and the ortho-domes r (101) and

At the

ends,

the pyramid n (111) is generally the most prominent form, while the other forms shown in Fig. 344 are the clino-pinacoid b, the clino-

domes o

(Oil)

and k (012), the prism m

(110),

and the pyramid^? (111).

MONOCLINIC FORMS OF LOWER SYMMETRY THAN THAT PRESENTED BY THE NORMAL GROUP.
are, however, very rarely hemimorpTlic, having an axis of binary symmetry but no plane of symmetry the other has a plane of symmetry,

Two groups
One

are recognized,

but

observed.

is

but no axis of symmetry.

TRICLINIC SYSTEM.

In

this system the

forms are referred

to three axes, a,

ft,

and

and, intersecting at oblique angles, a, fi, c, of unequal lengths, and y (Fig. 345). The directions which are taken to represent the axes correspond to prominent crystallographic
features, but otherwise are arbitrarily chosen. Any one of the axes may be taken as the
vertical axis
c,

and

of the lateral ones, b is

the longer or macro-axis and a the shorter or For each mineral crystallizing brachy-axis.
in this system, the ratio lengths of the axes and the inclinations must be determined from the measurement of appro/?, and Y
,

In axinite, for example, priate angles. 131 82 54', ft = 91 52', and y and a

a:b:c =
32',

0.492 1
:

0.480

Forms of

the

Normal Group.

Axinite Type.
consists of two sim-

but neither Crystals of this group have a center of symmetry,

planes nor axes of symmetry.
central point.

Each form

ilar parallel faces, diametrically disposed with reference to a

Each form,

since it consists of only

two

parallel faces, has the

character of &pinacoid. It is convenient, however, to designate the forms according to their relations on the axes, as pyramids when intersect the three axes, as prisms or domes when

they

NORMAL GROUP.

215

they intersect two axes and are parallel either to the vertical or to one of the horizontal axes, and as pinacoids when they inter-

and are parallel to the other two. Pyramids. The form (111) (Fig. 346) consists of two similar faces, and is designated as a pyramid for the sake of convenience. Four entirely different forms are possible, each of which intersects
sect one axis
ti;e

axes at their unit lengths,

(111), (111), (111),

and

(111) (Fig. 347).

FIG. 346.

FIG. 347.

FIG. 348.

single

Pig.
(321),

346.

form can be more complex than the one represented by The symbol may be more complicated, for example
faces.

but the form can consist of but two

Prisms.

The forms

m (110)

and

(110) (Fig. 348)

each consists

of two similar faces, and the four planes constitute a triclinic prism, whose faces do not make equal angles with the terminal

plane

c.

Domes.

If the

forms are parallel to the 5

axis, for

example,

(101) or (101) (Fig. 349), they are called macro-domes-, and if parallel to the a axis, for example, (Oil) or (Oil) (Fig. 350), they are

called bracJiy -domes.

Pinacoids.

When

it is

reasonable to do

so, it is

customary to

select three prominent faces of a crystal to represent the macro-

FIG. 349.

FIG. 350.

FIG. 351.

pinacoid a (100), the br achy -pinacoid b (010), and the ~base or basal pinacoid c (001) (Fig. 351). These three forms are important, because their intersections determine the axial directions.

216

TRICLINIC SYSTEM.

Combinations.

some

of

The following illustrations will serve to show the variations in habit which may result from the combi-

Since the crystals have neither a plane nor an axis of symmetry, any face may be taken as a pyramid, prism, dome, or pinacoid. In orientating a triclinic crystal the most

nation of triclinic forms.

important thing to be considered

is

the adoption of such a position

that the prominent faces will have as simple indices as possible. It should be noticed, in studying the examples given below, that the crystals have been so orientated that, in most cases, the promi-

nent forms are the pinacoids a

(100), b (010),

and

c (001),

and the
a

(110) and J^~(110), all having very simple indices. prisms Axes a ~b c = 0.492 1 0.480 Axinite (Fig. 352).
:
: :

82

M 28 m A p = 30 Prominent forms M A r = 45 the two and M terminated by the pyraprisms m

a A and

54',

ft

= 91
34',

52',

and y

== 131
55',

32'.

Angles
33',

m = 15
p

15'.

are

(110)

(110),

FIG. 352.

of the crystal

(111) and r (111), and the macro-dome s The exceptionally acute and obtuse angles (201). are conspicuous, whence the name axinite (ASit^

mids

an
94

axe).

AlUte
3',
ft

(Figs. 353 to 356).

Axes a:b:c
9'.

=
b

0.633
c

0.558
24',

=
c.

= 116

= 65

18',

MA

29',

and

y = 88
and

= 69

10',

m A M = 59

Angles

A = 86
The

mA

14'.

crystals are

FIG. 353.

FIG. 354.

FIG. 355.
l>

FIG. 356.

commonly flat (tables) with the brachy-pinacoid (010) prominent. Combined with this are the two prisms m (110) and Jf(llO), the base c (001), and the macro-dome x (101). The pyramids o (111)
and q
(111) are

often present.

Twins are common, often polysyn-

NORMAL GROUP.
thetic (Fig. 356), the pinacoid
~b

217

being the twinning-plane. The basal planes of polysynthetic crystals show a repetition of reentrant and salient angles and when the lamellae are numerous,
;

as is often the case, the basal plane, or cleavage-surface, shows a

series of fine striations (Fig. 87, p. 168).

The similarity between

albite

and the closely related mineral orthoclase of the monoclinic system (p. 211), may be seen by comparing their axial ratios and
Cyanite (Fig.
357).
:
: :

interfacial angles.

Axes a I c = 0.899 1 0.709 a = 90 5', ft = 101 2', and y = 105 44'. Angles a A = 73 56', a A c = 78 30', b A c = 86 45', and a A = 48 18'. The crystals are generally long and bladed, owing to the prominence of the macro-pinacoid a (100), FIG. and are seldom terminated by distinct faces. Axes a b c Rhodonite, variety Fowlerite (Fig. 358). a = 103 39', ft = 108 48', and y = 1.078 1 0.626 55'. 81 Angles c A a = 72 30', a A m = 48 33', = 92 49', c A m = 68 26', and c A Jfcf = mA 86 41'. The crystals are commonly somewhat The two tabular, with the base c (001) prominent. FIG. 358. m (110) and J/"(lIO) are common, while the prisms pyramids n (221) and k (221) are usually subordinate. Rhodonite = 92 49') is closely related to pyroxene (p. 210), in which (m A m A m = 92 50'. Axes Chalcanthite (Blue Vitriol) (Fig. 359). a:b:c = 0.566 1 1.055 or = 82 21', ft = 73 11', and y = 77 37'. Angles a A b = 100 41', a Am = 30 51', = 25 59', and m /\p = 52 20'. The crystals a A commonly have the two pinacoids a (100) and 5 (010) and the two prisms m (110) and (110) prominent, FIG. 359. and are terminated by the faces of the pyramid^? (111).
:

t>

218

THE THIRTY-TWO CLASSES OF CRYSTALS.

TEICLINIC FORMS OF

LOWER SYMMETRY THAN THAT PRESENTED

BY THE NORMAL TYPE.

Triclinic crystals

have been observed which do not have a

centei-

symmetry, but no minerals belonging to this class are known. On the crystals, each form consists of a single plane, but the
of

occurrence of any crystal face does not necessitate the existence

of one parallel to
it.

NOTE CONCERNING THE SYSTEMS OF CRYSTALLIZATION.

Although crystals are
classified into six systems, according to

their axial relations, each system is subdivided into groups with varying degrees or kinds of symmetry. Each of these subdivisions really constitutes a distinct class, characterized by & particular kind of symmetry, which a substance crystallizing in that class From purely mathematical considerations will invariably show. it can be shown that there are thirty -two possible classes to which
crystals can be referred,

and

all

but three of them have been ob-

served either among- minerals or artificially crystallized salts. The possible kinds of symmetry are sn'own in the table oppo-

The references will serve to indicate the important classes which have been described in the foregoing pages.
site.
.

'.;

PSEUDOMORPHOUS CRYSTALS.
Although the occurrence of a mineral in distinct crystals may generally be regarded as a proof of the homogeneous character and
purity of the material (p. 156), this is not always the case. A substance may either undergo chemical alteration or be replaced by
material of entirely different character without perceptible change in the crystalline form, and thus crystals result which have the

form of one mineral and the chemical composition of another. Such crystals are known as pseudomorphs (tyevdrfs, false, and
/7,

form).

THE THIRTY-TWO CLASSES OF CRYSTALS.

219

TABLE SHOWING THE SYMMETRY OF THE THIRTY-TWO CLASSES OF

CRYSTALS.
An
asterisk denotes the absence of a Center of

Symmetry.

System.

Isometric.

220

PSEUDOMORPHOUS CRYSTALS.

Pseudomorphs by Chemical Alteration of the Original Material. Crystals of pyrite, FeS by long exposure may become oxidized and hydrated, and partly or wholly converted into limonite (iron Thus pseudomorphs of limonite after pyrite rust), Fe O (OH) are formed. A similar change takes place when iron rusts from
2, 4
8

6.

a discarded rusty tool is found, the character of the implement may generally be determined from the shape of the mass of iron rust, even though the steel has wholly disappeared,
exposure.
If

and so, from the shape of a pseudomorphous crystal, the nature and name of the original mineral may generally be inferred. Other illustrations are the change by hydration and loss or gain of magnesium oxide, of the silicates chrysolite, Mg SiO and en2
4,

statite,

MgSiOs, to serpentine,

H Mg Si
4
3

2Mg SiO
a

MgO = H Mg Si O 2MgSiO +2H,Oplus MgO = H Mg Si O

4

+ 2H O
2

less

Pseudomorphs by Incrustation and Replacement. Often crystals of fluorite become coated with quartz, and subsequently the former is removed by solution or other agency, and the space
thus
left

vacant

is

wholly or partly

filled

by a deposit

of

quartz, thus producing pseudomorphs of quartz after fluorite. Another illustration is furnished by petrified wood. As the wood

decays the

silica

which

posited upon its of the wood in a remarkable manner.

dissolved in the percolating water is defibers, often preserving the delicate structure
is

Pseudomorphs Resulting from Molecular Change.

molten sulphur

When

is cooled, rather quickly, crystals belonging to the monoclinic system are formed, which cannot be preserved at ordinary temperatures, because they undergo a molecular change

Similar changes in molecular condition, without the addition or removal of chemical constituents, take place in nature, giving rise to pseudomorphs
to the orthorhombic modification
(p.

202).

of calcite after aragonite, rutile after ~brookite, amphibole after pyroxene, etc. These are also called paramorpJis.

STRUCTUEE.

STRUCTURE OF MINERALS.
In describing the structure of minerals a number of terms are conveniently employed which will need a little explanation.

Granular.
of galena.

When

a mineral consists of an aggregate of cryssize,

talline particles of

about the same

as marble

and some varieties

Compact. Earthy. A more or less firm consistency, resulting from a uniform aggregation of exceedingly minute particles, as
substance exhibits no crystal faces, although Massive materials (pieces :lt may possess a crystalline structure. of quartz, chalcopyrite, etc.) are more often encountered than wellcrystallized specimens.

kaolin (clay). Massive.

When a

no trace of crystalline structure exists. There are not many minerals which are truly amorphous, and they are not always easily distinguished from massive materials.

Amorphous.

When

Opal, amber, and obsidian (volcanic glass) are good examples. Columnar. When there is a parallel, or nearly parallel, group-

ing of prisms or columns, as illustrated by some varieties of

wollastonite and beryl. Fibrous. A structure similar to the foregoing, but in which the individuals are exceedingly

minute, as illustrated by some varieties

of

serpentine

(Fig.

360),

amphibole (variety asbestus), and gypsum. The fibers may often be

separated or pulled apart into fine Shreds. Minerals possessing a fine
is called satin- spar.
Fj ^ Fibrous Structure.
;

Serpentine.

fibrous structure usually have a silky luster

hence fibrous gypsum

Foliated.

When

a mineral separates easily into plates, as in

some

varieties of serpentine

and

brucite.

Micaceous.

structure similar to the foregoing, but in

which

$22

STRUCTURE.

the material can be split readily into exceedingly thin sheets, as

muscovite (common mica). Radiated. When columns,

fibers,

or foliae diverge from cen-

and pyrophyllite. Reniform and Mammillary. These are terms applied to rounded masses, usually with a smooth exterior, which have a retral points, as in pectolite (Fig. 361), wavellite,

FIG. 361.

FIG. 362.
Pectolite.

Radiated Structure.

Reniform Structure.

Kidney-iroii or

Hematite.

semblance either to a kidney or to mammae. They are illustrated by some varieties of hematite (Fig. 362) and malachite. Botryoidal and Globular. These terms are applied to rather
small rounded or spherical prominences, found in some varieties of smithsonite (Fig. 363), opal (hyalite) and other minerals.

FIG. 363.

FIG. 364.
Smithsonite.
Stalactitic Structure.

Botryoidal Structure.

Limonite.

Stalactitic.

When the material

occurs in pendants (icicle-like

calcite (cave-stone).

forms), as limonite (Fig. 364)

and some

StalaC'

CLEAA7 AGE.
tites

223
is

form in

cavities.

The material

deposited generally from

dripping water.

COHESION RELATIONS OF MINERALS.

Cleavage.
to break

Crystallized substances usually exhibit a tendency

more readily in some directions than in others, often yielding smooth surfaces which resemble crystal faces. This property is known as cleavage. The directions of cleavage are always parallel to possible crystal faces, and usually to faces with simple
indices.

Cleavage is a separation parallel to the molecular planes composing the crystal (Fig. 51. p. 157), and is due to the fact that
the forces which unite the molecules are weaker in certain directions than in others.

Some

substances, such as calcite, gypsum,

and

mica, can be cleaved with great ease. Such cleavage is designated as perfect, and if the cleavage-fragment is held in an appropriate
position, close to the eye, a perfect reflection of distant objects will

be obtained from

its surface. In some minerals cleavage is poor, or can only be detected with difficulty. In studying minerals the ease with which cleavage can be produced and its direction, or its

relation to the crystal form, should be carefully noted. Often the cracks in a crystal reveal both the presence and the direction of

cleavage.

To produce a cleavage, place the edge

of a knife-blade

or chisel on a crystal face, parallel to the direction in which the cleavage is supposed to exist, and strike a sharp, quick blow with

a hammer. In the isometric system cleavage

may be
;

cubic (Fig. 95, p. 170,

96, p. 170),

and Fig.

365), as in galena
;

and

halite

octahedral (Fig.
is

as in fluorite

or dodecahedral (Fig. 97, p. 170), as in sphalerite.

designated as basal or prismatic when parallel, respectively, to the faces lettered c or In the rhombohedral group it is often rlioinbo(Fig. 191, p. 187).

In the hexagonal system cleavage

Tiedral (Fig. 219, p. 193,

and

Fig. 366), as in calcite.

This

is

char-

by being equal in three directions, but not at right angles to one another.
acterized

224

PARTING.

In the remaining systems cleavage

is

called basal

when

it is

in one direction, parallel to the terminal face c (001) in the figures

FIG. 365.

FIG. 366.

Cubic Cleavage.

Galena.

Rhombohedral Cleavage.

Calcite.

pp. 179 to 217, illustrated by apophyllite in the tetragonal, topaz in the orthorhombic, and orthoclase in the monoclinic systems.

Cleavage

is

called pinacoidal

when

it is

in one direction, parallel

to the vertical pinacoids of the orthorhombic, monoclinic, or triclinic systems, as in stibnite (Fig. 283, p. 203) and gypsum (Fig.
322, p. 211),

where

it is

parallel to the faces

1)

(010).

In orthoclase

(Fig. 326, p. 211) there is a perfect basal cleavage parallel to c (001), and a less perfect cleavage at right angles to it, parallel to the clino-

pinacoid b (010). A cleavage is designated as prismatic when produced with equal ease in two directions, parallel to the faces

m (110) or a (100) of the tetragonal system (pp. 179 to 183), or parallel to the faces m (110) in the orthorhombic and monoclinic systems
(pp. 200 to 213).

Amphibole furnishes a good example

of prismatic

cleavage.
It is the case in some crystals that when they are strain or pressure there is apparently a slipping or subjected to gliding of the particles along certain molecular planes. This is

Parting.

accompanied at times by an overturning of layers of molecules into the position which they would occupy in a twin crystal. By this process a weakness along these planes is developed, and the crys-

talmay^ar^

or break with smooth surfaces.

This phenomenon

is

called parting

and is distinct, though not always readily distinfrom cleavage, from which it differs in that it takes guished,

FRACTURE.

225

place only wliere tJie molecular structure has been disturbed by pressure or other agency, while cleavage in a given direction can be produced as readily in one part of a crystal as another.

Magnetite shows no perceptible cleavage, but specimens from certain localities show a perfect octahedral parting (Fig. 367).

FIG. 368.

Twin Lamellae and

Basal
Parting.

FIG. 367.

Pyroxene.
Magnetite.

Octahedral Parting.

Pyroxene has a rather poor prismatic cleavage, but some crystals show twin lamellae very distinctly and parting parallel to the
basal plane (Fig. 368). Fracture. If a mineral has a poor cleavage, and separates or breaks almost as readily in one direction as in another, smooth,

curved surfaces often result

This kind of fracture
dal,
is

(Fig. 369).

called concTioi-

from

its

resemblance to the curved

It
is

surface of

a shell.

especially

characteristic of

such as

glass,

amorphous substances, and of minerals having a

poor cleavage, such as quartz, while it may occasionally be observed on minerals

which cleave
is

Fracture

readily, as calcite. said to be uneven when

;

FIG. 369.

rough, irregular surfaces are obtained

Conchoidal Fracture. Obsidian or Volcanic Glass.

hackly when a jagged, irregular surface like that of broken metal results and splintery when the substance breaks in
;

splinters or needles.

226

HARDNESS.

Tenacity. A mineral is said to be malleable when it can be beaten out into plates by hammering sectile when it can be cut
;

with a knife, so that a shaving results flexible when it bends readily, but does not resume its shape when the pressure is re;

lieved

elastic

when

it

bends and springs back to

its

original

position.

Hardness.
it

The hardness

of a mineral, or the resistance whicli

is

expressed in terms of a scale of liardness, consisting of crystallized varieties of the following ten minerals
offers to

being scratched,

Scale of Hardness.
1.

Talc.

3.

Calcite.

5.
6.

Apatite.
Orthoclase.

7.
8.

Quartz.

9.

2.

Gypsum.

4.

Fluorite.

Topaz.

10.

Corundum. Diamond.
point, or

The hardness

of a mineral is determined
it

by drawing a

a sharp corner of
scratch, while
scale.
it

across

erals in the scale of hardness until one is

smooth surfaces of the different minfound which it will just

Thus

if

will not scratch the next higher member in the a mineral will scratch calcite but not fluorite its
4.

hardness will be between 3 and

It is generally

a simple matter to determine the hardness of a but 'there are some cases where considerable care and mineral, judgment must be exercised. For example, a soft mineral may

crumble when drawn across a harder one, especially when the surface of the latter is rough, and leave a mark, similar to that of chalk on a blackboard, which readily rubs off and must not be

mistaken for a scratch.

hardness of minerals

Again,

it is difficult

to obtain the correct,

which crumble readily or crystallize in fine needles or scales, for when drawn across the surfaces of the minerals in the scale of hardness they break down and do not offer sufficient resistance to make a distinct scratch on materials which may be
considerably softer. In determining the hardness of minerals a knife-blade will be

found very useful. It will scratch apatite with some difficulty, but not orthoclase, and its hardness, therefore, is a little over 5,

LUSTER.

227

"With a

experience an approximation to the hardness of the softer varieties of minerals may be obtained by noting the ease with which they are scratched with a knife. The hardness of
little

window-glass
useful.

is

about 5, and some pieces of

it

will be

found very

and

its

An ordinary brass pin will scratch calcite but not fluorite, hardness is, therefore, a little over 3. The finger-nail will

scratch talc easily and gypsum with some difficulty. Crystals exhibit varying degrees of hardness in different directions, being softer parallel to a cleavage direction

than at right

angles to it. This difference, however, is usually not sufficiently great to be detected by the ordinary methods of testing hardness.

Cyanite furnishes a striking example, for in the direction of cleavage (parallel to the longer axis of the splinters) it can be
readily scratched with a knife, while at right angles to the cleavage the hardness is considerably greater than that of steel.

PROPERTIES DEPENDING UPON LIGHT.*

Luster.

The

luster of minerals, or their appearance

due to

the

reflection, absorption, or refraction of light, furnishes an important means of identification, and is described by the following

terms

lead or copper.

Having the luster and appearance of a metal, like Under this head those minerals are included which are opaque, that is, those which are not at all transparent when their thin edges are examined in a strong light. The powder
Metallic.

of an opaque substance
it

is

black or very dark, because the small

;

do not transmit any light therefore this particles constituting property may be usefully employed in detecting metallic luster. Pyrite and galena are examples of minerals with metallic luster.
Sub-metallic.

Dark-colored minerals which lack the true luster

* Though fully appreciating the importance of the application of polarized light in the study of crystals and the identification of minerals, it has seemed best not to include these methods in the present work. For a description of them tha student is referred to Idding's translation of Rosenbusch's Mikroskopische Physiographic der petrographisch
wichtigen Mineralien or to Dana's Text-book of Mineralogy.

228

STREAK.

of a metal are called sub-metallic.

Such substances are generally slightly transparent in very thin splinters and give dark powders,

although the colors are considerably lighter than those of the compact minerals. Chromite, limonite, and some of the dark varieties of sphalerite are examples of minerals with sub-metallic
luster.

Non-metallic.

Transparent minerals are here included.

If col-

orless, white, or light-colored they will give white powders, and if of decided colors their powders will be of lighter shades than

those of the compact minerals. For example, a dark-green epidote

yields a very pale green powder. Transparent minerals exhibit the following kinds of luster: Vitreous, like the luster of glass. Adamantine, like the luster of a

diamond.

Minerals possessing this luster have a certain brilliancy,

due to the strong refraction of light, i. e., they have a high index of Adamantine luster may be observed on some of the refraction. hard minerals used as gems and on cerussite and other transparent
salts of lead.

Resinous, or having the appearance of

resin,

as

if

shown by transparent varieties of sphalerite. Greasy or oily, as the mineral had a thin coating of oil over it, as shown by some specimens of serpentine and massive quartz. Pearly, like the This is due to the interference of light luster of mother-of-pearl.
in minute cracks (Newton' s rings).
It

may

usually be observed

on crystal faces

parallel to

which there

is

a perfect cleavage, as on

the basal planes of an apophyllite crystal. Silky, like a skein of silk. This may be observed on minerals which have a fine fibrous
structure.

Streak.

The streak

of a mineral is the color of its

powder.

Provided the material is not too hard, this may be quickly determined by rubbing it on a piece of white, unglazed porcelain,

and noting the color

this purpose.

of the powder, or

mark, which

is left.

Pieces

of unglazed porcelain, called streak-plates, are

made

especially for

Color.

The

color of minerals is a property

which should be

Carefully considered.

A mineral with

metallic luster will always

COLOR.

229

of color provided fresJi, unaltered material or a freslily broken surface is examined. Thus, the color of

show the same tone

On exchalcocite is steel-gray and of bornite brownish-bronze. to the air and light, however, the surfaces of minerals with posure
metallic luster
dull or tarnished and present quite a from that of the fresh material. For example, chalcocite becomes black, and a fresh surface of bornite tarnishes to a purplish tint in less than a day. A mineral without metallic

may become

different appearance

luster has always a definite color provided

contains a constituent, like copper, iron, or chromium, which has the property of coloring its compounds. Thus, copper minerals are generally green or blue,
it

those containing iron and chromium generally green, though of different shades, while chromates are red or yellow. Often, however, the color of a mineral

with non-metallic luster

is

variable, as

illustrated

by fluorite, which is colorless, yellow, pink, green, and violet, or by tourmaline, which ranges from colorless, or white, through varying shades of pink, green, blue, and brown, to black. The causes for the variation in color of some minerals cannot be detected, since it takes such minute quantities of certain materials In a few cases the color disappears to impart color to minerals. upon the application of heat, and is supposed to be of the nature
of an organic pigment. In the majority of cases, however, variation in color is due to the admixture of some isomorphous constituent

which has the property

of absorbing light.
,

the diopside variety of pyroxene, CaMg(SiO,) 2 is pyroxenes containing the isomorphous iron molecule CaFe(SiO s ) vary from light to dark green, depending upon the amount of iron

For example, colorless, but

which they contain. As explained on p. 7, the variations in the color of sphalerite, from colorless, or nearly so, when pure ZnS, through brown to black, depend upon the amount of the isomorphous iron sulphide molecule FeS which the mineral contains. Frequently a mineral is colored by some foreign constituent with which it is mechanically mixed. Thus jasper is quartz colored red or brown by an admixture of either hematite or
li

230

FUSIBILITY.

PROPERTIES DEPENDING UPON HEAT.

Fusibility.

The ease with which substances

fuse, or their de-

gree offusibility, admits of approximate determination, and is of great assistance in the identification In testing fusibility, of minerals.

uniform dimensions should be employed, and pieces about 1.5 mm. in diameter (Fig. 370) may be assplinters of nearly

sumed

as the standard size.

The

splinter

should be held in the platinum forceps so that its end projects beyond the metal, then
FIG. 370.

Method ment when

of holding a fragof standard Size testing for the degree of fusibility.

.. splinter or a fragment with a very thin edge

.
.,

heated as shown in the figure. Provided its edges do not become rounded, a much finer

should be tested before deciding that the material is infusible. The fusibility of a mineral is determined by comparing its fusibility

with that of a fragment of the standard size from the

:

fol-

lowing scale

Scale of Fusibility.*
r
1.

Stibnite,

rather large fragment fuses easily in

-4

Sb,S,

a luminous lamp or gas flame. Fusible in la closed glass tube below a red heat.

C
2.

Chalcopyrite,

CuFeS

J
|

fragment of the standard size fuses ra ther slowly in a luminous lamp or gas
flame.

small fragment fuses in a closed ^ glass tube at a full red heat.

C

fragment of the standard

size

fuses

3.

Almandine
Garnet,
-<j
.
I

readily to a globule before the blowpipe.

Fe Al (SiO
3

4) 3

In a luminous lamp or gas flame only the very finest splinters or thinnest edges are

I rounded.
*

With

who mnde
range

the exception of chalcopyriie the scale here adopted is that of Von Kobell, use of natrolite as No. 2. Ntilrolite, however, seeuis poorly chosen, for the between stibnite and natrolite is considerable, while between uatrolite and garnet
is slight.

the difference

PYROELECTKICITY.
f
4.

231

The edges
pipe.

of a fragment of the standard

Actinolite,
3
4
.

size are readily

rounded before the blowfiner

Ca(Mg,Fe) (SiO 3 )

A much

splinter

is

easily

fused to a globule.

,,

size are
j
^

The edges of a fragment of the standard rounded with difficulty before the

K A1S* O

kl

w PiP e

I*

ig

on ly when very fine splinters

are
^
6.

employed that the material can be fused

to

a globule.

Bronzite,
3
.

(Mg,Fe)SiO

Only the finest points and thinnest edges become rounded before the blowpipe.

Glowing. Some minerals glow, or emit a bright light, when heated intensely before the blowpipe. This is a property of infusible substances, and the oxides of calcium, magnesium, zirco-

marked degree. Fragments of and zircon ZrSiO glow when inMg(OH) tensely ignited. The Auer von Welsbach light is obtained by heating a mantle of thorium oxide with a Bunsen-burner flame. Phosphorescence. Some minerals when gently heated become luminous and emit light for a longer or shorter period. This
nium, and thorium possess
calcite
it

in a
2
,

CaCO

3,

brucite

4,

property,

known

as phospJiorescence,

may

fragments of a mineral in a closed tube,

be tested by heating and best in a dark room

.

Many

varieties of fluorite phosphoresce beautifully, with purple or

green light.

Some minerals phosphoresce when they are struck or

rubbed

others after they have been exposed to sunlight or to an

electric discharge.

Pyroelectricity.

Some minerals when they undergo a change

electric

of temperature

become

and have the property

of attractis

ing light bodies.

This property,

known

as pyroelectricity,
i.

espe-

cially characteristic of TiemimorpJiic substances,

e.,

those which

show an unlike development of crystal forms at opposite extremiTwo kinds of electricity are ties of an axis of symmetry (p. 164). at one end and negative at the other. always developed, positive To detect pyroelectricity a crystal, held in the platinum forceps, is heated gently (not much above 100 C.), and as it cools it is brought

232

PYEOELECTRICITY.

near some small bits of tissue-paper, which, will be attracted. A cat' s hair which has been rubbed between the fingers and become
positively electrified is excellent for detecting pyroelectricity, for it will be attracted to that end of the crystal where negative elec
tricity prevails,

and repelled by the other. A hair for this purpose be fastened to a cork by means of sealing-wax and kept in may a vial. Another very beautiful method is tried with a mixture ol
about equal volumes of red oxide of lead and flowers of sulphur. The mixture is kept in a vial, over the mouth of which two or

may

three thicknesses of fine bolting-cloth are tied, so that the powder be sifted out slowly. When agitated, the red oxide of lead

becomes positively, and the sulphur negatively electrified, so that when the mixture is dusted upon an electrified body the red
oxide of lead will be attracted to that part where there is negative, and the sulphur to where there is positive electricity. Experiments in pyroelectricity may be made with the lighkcolored
varieties of tourmaline or with crystals or fragments of calamine.

Generally the experiment

succeeds

best

when a

rather small

fragment

is

employed.

PROPERTIES DEPENDING UPON WEIGHT.

Specific Gravity.

The

specific

gravity of a substance

is

the

ratio of its weight to the weight of

an equal volume of water. For example? quartz has a specific gravity of 2.65, and is, therefore, two and sixty-five hundredths times heavier than water. Specific gravity is a definite property of all minerals which
show no variation in chemical composition, and, when carefully determined, can be used to great advantage as a means of identifi There are, however, several conditions which must bo cation.

carefully considered.
1.

It is of the If it is

pure.

utmost importance that the material should be not, there is little or no advantage to be gained by
gravity.

taking
2.

its specific

pure, transparent fragment of a mineral will apparently

specific gravity

have a somewhat higher

than a piece which

is full

SPECIFIC GRAVITY.

233

which tends to make the minAir can generally be expelled from cracks by boiling eral lighter. the fragment in water for some minutes, when an accurate determination may be made.
of cracks, as the cracks contain air
3.

It is difficult

specific gravity of porous, earthy,

and often impracticable to obtain the correct and fine fibrous, or scaly, min-

erals because of the air which they confine. Moreover, the chances of their containing impurities are also great and must be taken into consideration.
4.

may

variation in chemical composition exhibit considerable range in specific gravity. This is espe'a

Minerals which show

an isomorphous mixture of two molecules with widely different molecular weights, as in the case of the niobate and tantalate of iron, explained on p. 7. In such cases,
cially true

when

there

is

however, the specific gravity determinations may have great value, as furnishing a means of approximately determining the proportions of the

isomorphous constituents.

In the tables for the determination of minerals, pains have been

taken to give, as accurately as possible, the specific gravity of the pure crystallized varieties of each mineral. Variations from these
figures should be small, provided the material that is tested is

pure and its specific gravity is taken correctly. The usual method for taking specific gravity
stance in air and then

is

to

weigh a subdifference in

when immersed

in water.

The

is the weight of a quantity of water equal to the volume of the substance, for a body when immersed in water is buoyed up by a weight equal to that of the water displaced. If

these values

Wa

is

the weight of a substance in air and

in water, its specific gravity
is

Ww its weight when

Wa

immersed

found by dividing

by Wa - Ww.
For very accurate determinations the weights should be taken on a chemical balance. The material is first boiled in water for some minutes to expel the air, then allowed to cool in the water
to the temperature of the room.
It is

in a wire basket, suspended from the

arm

then conveniently placed of a chemical balance

234

SPECIFIC GRAVITY.
fine

by a very

platinum wire (Fig. 371), and the weight in water determined, from which the weight of the empty basket in water should be deducted. The material is then
weighed, after being thoroughly
dried.

For practical

purposes corrections

for

temperature may be neglected, for they will be trifling if the weighings are made at the temperature of an ordinary livingroom.

For quick
will

results in the identification

of minerals, the following simple

methods

be found convenient and

sufficiently

reliable for all ordinary purposes.

The Spring or Jolly Balance.

this
FIG. 371.

With

Method
ket

apparatus (Fig. 372) the relative weights of a substance are determined

,-,

of hanging wire bas- , / i ^ 7 j> on balance beam for by the stretch of a spiral substances in weighing q--^Two -nan<* arp 8 gwater. (Wire basket at the P

rm

side

carried at the lower end of

;

the spring the upper one c being in the air and the lower one d in water which is in a
glass resting

upon the

sliding platform B.

The

stretch of the spring is read

is

from a scale which

engraved upon a mirror fastened to the upright A. A white porcelain bead at serves as a mark

for noting the position of the spring with reference to the scale. It is evident that in order to

make

these readings correctly, the eye must be on the same level as the bead. This is accom-

plished by bringing the eye into a position where the top of the bead and its reflection in the mirror
coincide.

The pans being empty and the lower

one d being suspended in the water near the bottom of the glass, the position of the bead m
is

FlG 372 Spring or Jolly Balnnce for Specific

-

noted on the

scale,

= x.

fragment of mineral,

sufficient

SPECIFIC GRAVITY.

235

somewhat more than one half the length of the scale, is then placed in the upper pan and the platform lowered until the spring comes to rest, the pan d occupying the same relative position in the water as before, when the Hence y x is the position of the bead is again noted, = y. in air. The fragment is now transferred to the lower pan, weight and the platform raised until d occupies the same position in the
to stretch, the spring

water as before, when the position of the bead is again noted, = z. Hence y z is the loss of weight in water and the weight in air divided by the loss of weight in water gives the specific gravity.
^

The Beam Balance. This is a simple piece of apparatus (Fig. The beam of wood is supS73) which can be easily constructed.
6

FIG. 373.

Beam

Balance for Specific Gravity, ^th Natural Size.

ported on a fine wire, or needle, at b and must swing freely. The long arm be is divided into inches and tenths, or into any decimal
scale,

commencing

at the fulcrum b

the short

arm

carries a double
is

arrangement of pans, so

and the other

in water.

suspended that one of them A piece of lead on the short

in the air

arm

serves to

almost balance the long arm, and, the pans being empty, the beam is brought to a horizontal x>osition, marked on the upright, near c, means of a rider d. A number of counterpoises are needed, by
to be of any specific denomination as it is their on the beam and not their actual weight which is recorded. position Most handy are bits of bent wire which may be used as shown at A. The beam being adjusted by means of the rider d^ a frag-

which do not have

ment
is

of mineral is placed in the

upper pan and a counterpoise

of the long arm, will

chosen,

which, when placed near the end

236
it

SPECIFIC GRAVITY.

into a horizontal position. The weight of the mineral in air, TFa, is given by the position of the counterpoise on the scale. The mineral is next transferred to the lower pan, and the same

bring

counterpoise

is

brought nearer the fulcrum b until the beam

becomes again horizontal, when

mineral in water,
cific

Ww.

Wa

position gives the weight of the divided by gives the speits

Wa

Ww

gravity.
materials,

The balance has been repeatedly tested with pure

the variation from determinations

and

made on

a chemical balance has

never exceeded two in the second place of decimals. It is reliable, quick, and sufficiently accurate for all ordinary uses. The Heavy Solution. By treating 50 grams of mercuric iodide

and 40 grams

of potassium iodide in a porcelain dish, or casserole, with a little water, and evaporating until a crystalline crust begins

to form, about 30 cubic centimeters of a yellowish-green solution are obtained, which has a specific gravity of about 3.15. This may be

cleared

by

filtering,

dilute solution

may

be brought to

diluted with water to any extent, and the its maximum concentration by

keep indefinitely without decomposition, proevaporation. a few drops of mercury are added to it. It is very poisonvided In determining the specific gravity of a mineral by means of ous.
It will

the heavy solution, a fragment is placed in it, and then, by adding water cautiously, the specific gravity of the solution is lowered
until

becomes exactly equal to that .of the mineral, when the fragment will remain suspended in any position, neither sinking
it

The specific gravity of the solution may then be some of the methods described beyond. taken by The Westplial Balance. This consists of a metal beam (Fig. 374) with its long arm from I to 7i divided into tenths. A glass sinker r loaded with mercury, is suspended from li by means of a fine platinum wire, and the apparatus is so constructed that, with the sinker in air, the beam-pointer can be brought to zero on the scale s by means of the set-screw o. Four wire riders w are needed, of such
nor
floating.

a weight that one

pointer to zero

of them,

when hung
is

at

7^,

will bring the

beam-

when the

sinker

immersed

in water.

There are

SPECIFIC GRAVITY.

237

also needed

two lighter

weight. When riders are applied, as illustrated in the figure, until the beampointer stands opposite zero. The two ^mY-riders at the end and
r

one ^V and the other T ^Q- of the unit the sinker r is immersed in the heavy solution the
riders,

FIG. 374.

Westphal Baluuce

for

Taking the

Specific Gravity of Liquids.

one at 6 on the beam indicate a

specific gravity of over 2.6.

The

TV and yi^ riders, both at 5, furnish the second and third figures from the decimal point and indicate that the specific gravity
of the solution is 2.655.

The beam-balance (Fig. 373) may also be employed. sinker similar to r (Fig. 374) is suspended from a position marked by a notch near the end of the long arm. By putting shot in the pans and using the rider d the beam is brought to a horizontal position with the sinker r in air. The sinker is then immersed in the heavy
solution and a weight is selected, which, when placed near the end of the beam, will bring the latter to a horizontal position. The position of this weight gives relatively the weight of the heavy solution displaced by the sinker. After washing, the sinker
is

immersed in water, and the same

weigJit is placed nearer the

238

SPECIFIC GRAVITY.

fulcrum until the beam becomes horizontal.

The position

of this

weight gives relatively the weight of the water displaced by the sinker. The larger weight divided by the smaller gives the desired
specific gravity.

be found convenient, in the identification of a gem, to use the heavy solution for comparing an unknown with a known
It

may often

mineral, as follows

and a known
in the

stone supposed to be beryl crystal of beryl are placed together

:

heavy solution, and water is added to determine whether they sink and float together, i. e.,
whether they are identical in
specific gravity.

The heavy solution may

also be used for obtain-

ing a mineral in a state of purity when mixed with others of different specific gravity. The material is
pulverized and sifted to a uniform grain, then introduced into the heavy solution. The specific gravity

may

then be adjusted, first so that everything heavier than the desired mineral will sink, and then
so that everything lighter will float.

The

separa-

most readily accomplished ratus shown in Fig. 375.

tion can be

in the appa-

FIG. 375.

Besides the potassium mercuric iodide solution, which is the cheapest, and also the easiest to pre-

Separately Funnel, i Natural Size.

pare and to manipulate, the following have proved .11 J-T * /^TT T -^\ very useful methylen iodide, CH,!,, with a maxi,
:

mum

specific gravity of 3.33,

a,

and acetylen tetrabromide, f CHBr,

CHBr

with a specific gravity of 3.01, both of which may be diluted with benzol and barium mercuric iodide, \ with a maximum
;

specific gravity of 3.55.

The double

salt, silver

thallium nitrate,

giving a clear liquid with a maximum specific gravity of over 4.5, which may be diminished to any desired extent by adding hot water.

melts at 75

C.,

* R. Branus, Jahrbuch fur Mineralogie. 1886, Vol.

f ; C.

II, p. 72.

Krystallograpliie. 1898, Vol. XXX, p. 73. Rohrbach, Jahrbuch fur Mineralogie, 1883, Vol. II, p. 186. J. W. Retgers, Jahrbuch fiir Mineralogie, 1893, Vol. I, p. 90 ; Author, of Sci., 1895, Vol. L, p. 446.
Zeitschrift
1'iir

W. Muthman,

Am.

Jour,

CHAPTER

VI.

TABLES FOK THE DETERMINATION OF MINERAL SPECIES BY MEANS OF SIMPLE CHEMICAL EXPERIMENTS IN THE WET AND DRY WAY

AND BY THEIR PHYSICAL PROPERTIES.

INTRODUCTION TO THE TABLES.
In the
are

GENERAL CLASSIFICATION of the tables (p. 245) minerals divided into two groups I, WITH METALLIC OR SUB-METALLIC
:

LUSTER

II,

WITHOUT METALLIC LUSTER,

According to the ex-

planations on pp. 227 and 228 this division depends upon the fact whether the minerals are opaque and give black or dark streaks, or transparent and give white or light-colored streaks. Since,

whether the luster shall be considered metallic or non-metallic is, at times, wholly a matter of judgment, pains have been taken to
place

minerals whose luster might be considered doubtful in both sections. A further subdivision of each group depends upon whether a mineral is fusible or infusible. The directions

many

given on pp. 33 and 230 concerning fusion must here be carefully considered. In making the test, the degree of fusibility and per-

haps some behavior, such as flame coloration, may be recorded, which will be of service in the identification of the mineral. Each
section is then further subdivided, the divisions being based

some chemical constituent which may be readily detected,

the behavior with acids.

or

upon upon

In the tables

p.

246

et seq.,

the two vertical columns at the left

give, respectively, the

General Characters of groups of minerals and the Specific Characters of individual species, based, in most cases, upon simple blowpipe or chemical reactions. In the vertical

columns headed Species the names of the minerals are given

since the tables are intended to include all of the minerals

and,

which

are recognized as distinct species, this number is necessarily large, amounting to nearly 800 names. To facilitate the identification of
239

240

INTRODUCTION TO THE TABLES.

a single species from this large number the names are printed in three ways. Those in CAPITALS indicate common minerals, that is,
the ones which are found abundantly and are useful in the arts, or as ores of the metals, or are important geologically as constituents of rocks.

Those in

Fuii-faced

T ype indicate

minerals which

are valuable or important, but which do not occur often enough or in sufficient quantity to be considered as common. Names in
smaii type

It will probably be found that out of one hundred specimens to be identified fully usually seventy-five wiJl be the common minerals, printed in CAPITALS, With perhaps twenty Intermediate and five rare.

indicate rare minerals.

In the remaining columns the following important properties are recorded Chemical Composition, pp. 3 to 9 Color, p. 228 ;
: ;

Streak, p. 228 Luster, p. 227 Cleavage and Fracture, pp. 223 to 225 Hardness, p. 226 Specific Gravity, p. 232 Fusibility, p. 230 ; Crystallization, pp. 155 to 219.
;
;

METHOD OF USING THE TABLES.

The way in which the
following examples
Celestite.
:

tables are used

may

be illustrated by the

Referring to the General Classification on p. 245 and examining the mineral, it will be seen that it is without metallic luster, and therefore belongs in Group II. A small fragment heated
in the forceps before the blowpipe fuses rather readily, about 3.5 according to the scale of fusibility (p. 230), thus determining the

mineral to be in Section B.

It

should be noted that a red coloration

was imparted to the flame, indicating, according to the table of flame coloration on p. 136, probably either strontium or lithium. The mineral is not to be found in Parts I and II under B, because when its powder is fused with sodium carbonate on charcoal it
does not yield a metallic globule, and when fused alone it does not It must, therefore, be in the yield a black, magnetic mass. remaining Part III. It may readily be proved to be in Division 1

under Part

III, for

when

a fused fragment

is

placed on moistened

INTRODUCTION TO THE TABLES.

turmeric-paper,
trial will
it

241

shows an alkaline reaction.

is

Further, a test-tube

show that the mineral

in section b on page 273.

insoluble in water, and hence is Referring to that page the first section

under General Characters comprises carbonates, which dissolve in hydrochloric acid with effervescence. A test-tube trial of some of
the powdered mineral under examination indicates that it is very insoluble in acids, and therefore not a carbonate. That the mineral

belongs to the next section which comprises sulphates may readily be proved by fusing a little of it with sodium carbonate and
charcoal-powder, and thus obtaining a mass which gives a dark
stain

when placed on moistened

silver.

The mineral, moreover,

is difficultly

gives no water in the closed tube, and

boiling, dilute hydrochloric acid, as

soluble in

ment made when

testing for

shown by a previous experia carbonate. Under Specific Charac-

ters, the crimson flame coloration, tried best on platinum wire as directed on p. 35, determines the mineral to be celestite, strontium

sulphate,

SrSO

The physical properties given in the horizontal

:

section should correspond Color, colorless or white; Luster mtreous ; Cleavage of two kinds, perfect in one direction, basal, and less perfect in two directions, prismatic, so that a form like Fig.
273, p. 201,

may
;

be produced
is

Hardness 3 to

3.5,

the material
;

scratches calcite and

readily scratched

by

fluorite

Specific
;

gravity 3.97

Fusibility 3.5, which was

determined at the outset

Crystallization, orthorhombic, crystals being perhaps like Figs. 278 or 279, p. 202. If the specific gravity had been taken at the begin-

ning

it

would have served

to distinguish celestite

from

all

the

other minerals in Division

1, b,

pp. 273 and 274, for there are none

which come
or streak,
is

at all close to 3.97.

CJiromite.

The

color of this mineral

;

is

black,

dark brown

hence the luster

classified in

may

and the powder, be considered as

I,

sub-metallic,

and the mineral

Group

p.

245.

At

the
5

and

beginning, the hardness may 6, and the specific gravity as 4.6.

is

be determined

as

between
therefore

When
;

heated before the

is

blowpipe there
in Section B.

no indication of fusion
1,

the mineral

Division

under B, includes minerals containing

242

PRECAUTIONS IN THE USE OF THE TABLES.

iron,
it

which become magnetic after heating, but if a trial is made will be found that the mineral does not become magnetic. In

Division 2 the minerals containing manganese are included. test made with borax in the oxidizing name, as directed, gives a

bead which

yellow when hot and yellowish green when cold. This does not indicate manganese, but is a decided reaction for
is

chromium, as may be seen by referring to the table of reactions obtained with borax on p. 148. Since the mineral fails to give reactions for iron and manganese, it must belong in Division 3 Not
belonging to the foregoing divisions, p. 256. Referring to this page in the column General Characters, the mineral cannot be in the
first

section because of its hardness.

It

is,

however, in the second

section, since the borax-bead test, previously made, has indicated the presence of chromium. This reaction, as well as the determi-

nations of

FeCr,O

hardness and specific gravity, agree with chromite, A test for iron may be made with the FeO.Cr 2 O
a
.

sodium carbonate on charcoal, as directed magnet under Specific Characters. Had the chromite been considered as being without metallic luster, Group II, p. 245, it would have been found under C, Division 5, b, p. 298. Precautions in the Use of the Tables. The system adopted
after fusion with

in the construction of the tables is that of eliminating one

of minerals after another until a species
is

group

found, whose properties, to the mineral that is being as given in the table, correspond The process of elimination and identification is based tested.
largely

upon a

series of

chemical tests which, in almost

all cases,

give an insight into the character of the material. There is danger, however, that one may become so absorbed in following the tables mechanically, with the sole idea of determining the name of

the species, as to wholly lose sight of the importance of making a careful study of the chemical reactions and physical properties of

the minerals.

It

should be distinctly understood that

little

or

nothing
mineral.

is to

be gained by simply determining the name of a The chief aim should be to obtain a thorough faiowl-

edge of the chemical composition, physical properties, and gen-

PRECAUTIONS IN THE USE OF THE TABLES.

eral appearances
its

243

and
and

uses

and

relations

associations of a mineral, not only that may be understood, but also that it may be
identified

easily recognized

The general plan and arrangement

hered to rather closely, for
tion, that
if

when again encountered. of the tables must be

ad-

they are applied in the reverse direcis, backwards, they may not lead to the desired result. For example, if a mineral has metallic luster, is fusible, and gives a reaction for sulphur, it does not necessarily belong to Division 5

under

I,

(p. 245),

(Division 1)
is,

most of the minerals containing arsenic and antimony (Division 4) also contain sulphur. It
for

therefore, not correctly determined as belonging to Division 5

until proof has been obtained, not alone of the presence of sul-

phur, but also of the absence of arsenic and antimony, as well as of the rare elements selenicum and tellurium (Divisions 2 and 3).

The
If it is

tables are adapted to the determination of

pure minerals.

thought that a mineral is not pure the nature of the impurity must be taken into careful consideration. Thus, for exIf some ample, many minerals are associated with calcite, CaCO
3
.

of this

is

included in material that

is

being tested

it

will cause a

slight effervescence with acids and an alkaline reaction when the ignited material is applied to moistened turmeric-paper, although both reactions are probably entirely foreign to the mineral which

The best and almost the only rule to one' s judgment. It would be impossible guide one in such cases to devise blowpipe methods to meet the contingencies arising from the various mixtures of minerals. The one thing of the
it is

desired to determine.

is

very utmost importance is the assurance of the purity and homogeneous character of a mineral. Since, in most cases, only a very
required for the necessary tests, by careful selection enough can generally be secured in a pure condition.
little

material

is

RECORD OF MINERAL TESTS.

A careful record should be

it

may

kept of all tests as they are made. be found convenient to record them, together with the

244

RECORD OF MINERAL TESTS.

physical properties, upon blanks similar to the accompanying sample. It is not intended that every test for which a space has

been allotted should be made, but a convenient place has been furnished where the prominent blowpipe reactions may be recorded,
provided tests in the closed or open tubes or with the fluxes, have been made.
etc.,

Structure

System of

crystallization

Cleavage or fracture
Luster
Streak
Fusibility

Color

Hardness

Sp. Gr.

Flame

color

Effect of acids

aud reactions with the solution

Closed tube

Open tube
Alone on charcoal

With With

fluxes on charcoal
fluxes

on platinum wire.

Miscellaneous

NAME
Per cent of chief constituents

COMPOSITION.

Mode and

place of occurrence

Associations

Uses

Number
*
Fifty of these blanks,
net.

Date

..

bound

in

book form, may be obtained from the publishers.

50 cents,

(Page 245.)
/

ANALYTICAL TABLE
SHOWING THE

GENERAL CLASSIFICATION
OP

MINERALS.
ABBREVIATIONS USED IN THE TEXT OF THE TABLES.
Amorph... Amorphous. Approx... Approximately. Before the blowpipe. B. B
Botryoid.. Botryoidal.

Isom. Tet. Isometric Tetrahedral.

iso.

w.

Isomorphous with.

Marnin.... Mammillary.

Mammill.. Mammillary.

C
Capill

Cleavage.
Capillary.
Class.

Mass
Moiiocl
. .

Massive.
.

Mouoclinic.

01

Na 9 CO,
Oct

Sodium carbonate.
Octahedral.

Colum
Cryst Direc

Columnar.
Crystalline; in crystals. Direction.

O.F
Orthorh
per Pinac
.

Oxidizing flame. Orthorhombic.

Perfect; referring to cleavage. Piuacoidal; in one direction. Prismatic.

F
Fig
Fol

Fracture.

Figure.
Foliated.
Fusibility.

Fus Gran

Prism Pseudom.

Pse u do in o rphous.
Pyramidal. Radiated.

Granular.

Pyram
Radiat

H
HC1

Hardness.

Hydrochloric acid.
3

R.F
Sp. Gr.
. . .

Reducing

flame.

HNO

Nitric acid.

Specific Gravity.

H,SO 4

Sulphuric acid.

Sph
Tabul Tar

Hemiinor . Heminiorphic. Hexagonal. Hexag Hex. Rh.. Hexagonal Rhombohedral,

Incrust.... Incrusting; incrustation.

Spheuoidal. Tabular.
Tarnish.

Tetrag.... Tetragonal.
Tet. Sph.. Tetragonal Sphenoidal.

Isom

Isometric.

U
Vol
.

Usually.
.

Isom. Pyr. Isometric Pyritohedral.

Volatile.

N.B. The chemical symbols of the elements, together with the valences which they ordinarily exhibit in mineral combinations and their atomic weights, will be found in " Reactions of the Elements," pp. 41 to 134. Chapter III

245

GENERAL
GENERAL

CI

locating a mi Success in using the folloiving fables depends ivliolly upon C initial reactions, as given in this ve In testing the solubility of minerals the importance of using
\.

MINERALS WITH METALLIC OR SUB-METALLIC LUSTER.

the color of their powder, or the: Minerals Laving metallic luster are opaque; hence black (p. 227). The minerals with sub-metallic luster whic streak is dark though not necessarily dark-colored streaks. Many dark-colored minerals who* are included in this section all give

NOTE

is

in Section doubtful have been placed here, and also

II.

A.
1.

FUSIBLE

FROM

1-5,

OR EASILY VOLATILE.
PAC;

2.

3.

a volatile sublimate of Arsenious Roasted in the open tube, or B. B. on charcoal, give Section 4 Oxide(p. 48). Compare Antimony, the characteristic radish-like Roasted in the open tube, or B. B. on charcoal, give an azure-blue color to the reducing flame (p. 107) Selenium. Impart H 3 S0 4 and gently heated, the acid Treated in a dry test-tube with 3 cc. of concentrated
<

2 2

4.

assumes a reddish-violet color characteristic for Tellurium (p. 124) a dense white sublimate of Roasted in the open tube, or B. B. on charcoal, give
that of arsenic Antimony (p. 44). The sublimate is less volatile than of the odor Sulphurous Roasted in the open tube, or B. B. on charcoal, give but do not give the reactions of the preceding divisions (p. 118),

2-

Oxide of

5.

Anhydride
~

6.

Not belonging

to the foregoing divisions

B.-INFUSIBLE, OR FUSIBLE ABOVE

1
2.

Become magnetic

after heating B. B. in the

AND NON-VOLATILE. reducing flame, Iron (p. 84)

5,

2
lor,

bead minute quantity of material imparts to the borax

in O. F. a reddish-violet cc

Manganese (p.
3.

93)

Not belonging

to

the foregoing divisions

II.

MINERALS WITHOUT METALLIC LUSTER.

a da
strec

have such Minerals without metallic luster are transparent, although they may thin edges. The color of their powder, or their color that ihey transmit light only through very black (p. 228). is generally white or light-colored, never

NOTE

A.-EASILY VOLATILE, OR COMBUSTIBLE.

1.

Rapidly disappear when heated

B. B. on charcoal.

Only a few minerals behave thus

ONLY SLOWLY OR B.-FUSIBLE FROM 1-5, AND NON VOLATILE, OR PARTIALLY VOLATILE. Partl.-Give a METALLIC GLOBULE on charcoal.
1.

2.

3.

of Silver (p. 113). .......... a Fused B B on charcoal with sodium carbonate give globule dust give a globule on charcoal with sodium carbonate and charcoal Fused B. B. "' and a coating of Lead Oxide (p. 87). ; charcoal dust give a glol B. on charcoal with sodium carbonate and Fused B. and a coating of Bismuth Oxide (p. 54)

OSSIFICATION.
ral with certainty in the

345

group

to

which

it

belongs; hence

it is

evident that the

3IFICATION, should be tried with the utmost care. fine powder ground in an, agate mortar, can not be
?

overestimated.

PAGE
4.

5.

Fused B. B. on cLarcoal with sodium carbonate and charcoal dust give a globule of Antimony and a coating of Antimony Oxide (p. 44) Fused B. B. on charcoal with a mixture of equal parts of sodium carbonate and borax give a globule of Copper (p. 73). The powdered mineral on charcoal, after moistening with
hydrochloric acid, imparts an azure-blue color to the blowpipe flame

263

263

Part
1.

II.

Become Magnetic

after

Heating before the blowpipe in the

reducing flame, Iron.

Soluble in hydrochloric or nitric acid without perceptible residue, and without yielding gelatinous silica upon evaporation. Mostly Sulphates, Arsenates Phosphates.

and

266
269 270

2.

Soluble in hydrochloric or nitric acid and yield gelatinous silica on evaporation, or are decomposed with the separation of silica, Silicates
Insoluble in hydrochloric acid

3.

Part III.
1.

Do NOT

give

a metallic

globule,

and do

NOT

become magnetic.

Give an alkaline reaction on moistened turmeric-paper after intense ignition before t7ie blowpipe, held either in the forceps or, if very easily fusible, in a loop on platinum wire. Salts

of the Alkali
a) Easily
b)

and Alkali-earth

Metals.
water
.

and completely soluble

in

271

2.

Insoluble in water, or difficultly or only partly soluble. . Soluble in hydrochloric acid, but do not yield a jelly or a residue of silica on evaporation.

273
275

Mostly
3.

Arsenates, Phosphates

and Borates
Soluble Silicates.

Soluble in hydrochloric acid and yield gelatinous silica on evaporation. a) In the closed tube give water
b) In

278 279

4.

the closed tube give little or no water Decomposed by hydrochloric acid with the separation of silica, but without going wholly into solution and without giving a jelly on evaporation. Decomposable Silicates.
a) In the closed tube gi ve
b)

water

281

5.

In the closed tube give little or no water Insoluble in hydrochloric acid. Mostly Insoluble Silicates.

283 283

C.
1.

INFUSIBLE,

OR FUSIBLE ABOVE

5.

Give an alkaline reaction on moistened turmeric-paper after intense ignition before

pipe.

the blow-

Salts of the Alkali-earth Metals

289

2.

Soluble in hydrochloric acid, but do not yield a jelly or a residue of silica on evaporation.

Mostly
3.

Carbonates, Sulphates, Oxides, Hydroxides

and

Phosphates.....

290
294.

4.

Soluble in hydrochloric acid and yield gelatinous silica on evaporation. Soluble Silicates. Decomposed by hydrochloric acid with the separation of silica, but without going wholly into
solution

and without giving a

jelly

on evaporation.

Decomposable

Silicates

295
29fr
298-

5.

Insoluble in hydrochloric acid.

a)
b)

Hardness less than that of glass or steel Hardness equal to or greater than that of

glass.

Can be scratched by a knife Can not be scratched by a knife.

(Page 246.)

1.

MINERALS WITH METALLIC OE SUB-METALLIC LUSTEE.

A.
Fusible from 1-5, or Easily Volatile.
1.

DIVISION

Arsenic Compounds,

in part.

246

I.

MINERALS WITH METALLI'

A.
Fusible from
1

DIVISION
of arsenic
is

1.

Arsenic Compounds.

often obtained, p. 48.

heated before the blowpipe on charcoal, a whit Of other reactions for arsenic, roasting in the open tube is espec

When

N. B.
General Characters.

The minerals

in this division are chiefly

OR SUB-METALLIC LUSTER.
or Easily Volatile.

246

oating of arseuious oxide deposits at a considerable distance from the assay, and a garlic-like odor Y recommended, and, in some cases, heating in the closed tube gives decisive results.
arsenides and sulpliarsenites of Hie metals, p. 47.

Composition.

(Page 247.)

1.

MINERALS WITH METALLIC OR SUB-METALLIC LUSTER.

A.
Fusible from 1-5, or Easily Volatile.
1.

DIVISION
DIVISION

Arsenic Compounds,

concluded.
in part.

2.

Selenium Compounds,

247

I.

MINERALS WITH METAL!

A.
Fusible fron
1.

DIVISION

Arsci:

General Characters.

OR SUB-METALLIC LUSTER.
5,

24?

or Easily Volatile.
Concluded.

Compounds.
Composition.

(Page 248.)
I.

MINERALS WITH METALLIC OR SUB-METALLIO LUSTER.

A.

Fusible from 1-5, or Easily Volatile.

2.

DIVISION
DIVISION

Selenium Compounds,

concluded.

3.

Tellurium Compounds.

248

I.

MINERALS WITH METALLI

A.
Fusible from
2.

1-

Di VISION

Selenium

General Characters.

OR SJB-METALLIC LUSTER,
or Easily Volatile,

2-18

impounds.
Dmposition.

Concluded.

(Page 249.)

I.

MINERALS WITH METALLIC OE SUB-METALLIC LUSTER

A.

Fusible from 1-5, or Easily Volatile.

4.

DIVISION

Antimony Compounds,

in part.

249

L MINERALS WITH METALL1

A.
Fusible from
1t

DIVISION 4. Antimony Compounds. with the open tube may also be recommended.

Wbeu

heated before the blowpipe on charcoal

N. B.

Most of the minerals

in this division are the sulphantimoni-es

<

General Characters.

Specific Characters.

Name of

Species.

ID the open tube yields a white, slowly volatile, Antimony. crystalline sublimate of Sb 3 O 3 (p. 45).

Easily and completely volatil In the open tube yields when heated B. B. on charcoal. Do not give reactions for lead

S0 2 and

for the

most

sublimate o
in the closet
Livingstonite.

Reacts for mercury tube with Na a CO 8

when heated
.

Contains copper. When decomposed by 3 and treated with ammonia in excess, the solu- Bournonite. tion assumes a deep blue color.
Contains bismuth. Fused on charcoal with potassium iodide aud sulphur gives a -red sublimate.
Andorite. solution, filtered if necessary, gives with HC1 a precipitate of silvei Bronguiardite. chloride which is insoluble in hot water (differsilver.

HNO

Kobeliite.

Contain

The

HNO

lead. After carefully rousting on charcoal (p. 89) the ence from lead chloride, p. 89, 4). residue, when scraped up with Diaphorite. globule of silver is obtained by continued Na 3 CO 3 and fused in R. F., heating on charcoal in O. F. gives globules of metallic lead. Freieslebenite, The iodine tests for lead (p. 89 are very decisive. Contain tin. When heated in O. F. on charcoal When roasted alone on churcoa leave an infusible mass of oxide, which, when Cylindrite. (Kj-lindrite.) are nearly or completely vol mixed with Na 3 COa and charcoal

Contain

powder

atile.

aud fused
globule.

in

Oxidized by concentrated nitric acid, with the separation of metantimonic acid (p. 46, 6)
lead sulphate, and usually of sulphur.

R. F., gives a malleable metallic

Franckeite.

Zinkenite.

Plagionite.

Compare Galena (p. 251), which, when roasted alone on

charcoal,

Warren ite.

sometimes gives
resembling
(p. 88).

coating

that

of

antimony

Contain neither copper, bismuth, tin, nor silver. The minerals are distinguished by differences
in crystallization

Jamesonite. (Feather Ore.)

and physical properties.

Semseyite.
Boulancrerito.

Meneghiniie.
Geocrinite.

Kilbrickenite.

Spiboulangerite.

DIVISION

4.

Antimony Compounds.

Continued on next page.

OR SUB-METALLIC LUSTER.
or Easily Volatile.
ense white coating of oxide of antimony deposits near the assay
(p. 44).

249

The

test for

antimony

e,

metals.

The sulphur may be detected by

roasting in the open tube.

Composition.

(Page 250.)

1.

MINERALS WITH METALLIC OR SUB-METALLIC LUSTER.

A.

Fusible from 1-5, or Easily Volatile.

DIVISION 4

Antimony Compounds,

concluded.

250

I.

MINERALS WITH MBTALL1

A.
Fusible from
4.

DIVISION

Antimo

General Characters.

OR SUB-METALLIC LUSTER.
5,

250

or Easily Volatile.
Concluded.

Compounds.

Composition.

(Page 251.)

I.

MINERALS WITH METALLIC OE SUB-METALLIC LUSTER.

A. Fusible from
DIVISION
5.

1-5, or Easily Volatile.

Sulphides,

in part.

25"

I.

MINERALS WITH METALIJ

A.
Fusible from
1-

DIVISION 5. Sulphides. "When roasted in the open tube sulphur dioaide (sulphurous a piece of moistened litmus-paper placed in the upper end of the tube. The reactions of the

anli

will be

N.B. The minerals in this division are mostly sulphides of the metals. met with later on among the minerals without metallic luster.

Sulphides containing

General Characters.

OR SUB-METALLIC LUSTER,
or Easily Volatile.
ide) is

251

formed, which

may

be recognized by

its

odor,

and by the acid reaction which

it

imparts to

divisions should not be obtained.

enic,

antimony, selenium, and tellurium will be found

in the

foregoing divisions.

A few

sulphides

Composition.

(Page 252.)

I.

MINERALS WITH METALLIC OR SUB-METALLIC LUSTER.

A. Fusible from 1-5, or Easily Volatile.
DIVISION
5.

Sulphides,

continued.

252

I.

MINERALS WITH METALLI

Fusible from A.-l
L.

DIVISION

5.

General Characters.

3R SUB-METALLIC LUSTER.
5,

252

or Easily Volatile.
Continued.

licles.

(Page 253.)

I.

MINERALS WITH METALLIC OR SUB-METALLIC LUSTER.

A.
Fusible from 1-5, or Easily Volatile.
DIVISION
5.

Sulphides,

concluded.

DIVISION

6.

253

I.

MINERALS WITH METALL

A.
Fusible from
Di VISION
5.

1-

Su

General Characters.

OR SUB-METALLIC LUSTER.
.

253

or Easily Volatile,
Concluded.

jades.

Composition.

(Page 254.)

I.

MINERALS WITH METALLIC OR SUB-METALLIC LUSTER.

A.
Fusible from 1-5, or Easily Volatile.
DIVISION
6,

concluded.

I.

MINERALS WITH METALLI

A.
Fusible from 1
DIVISION
6.

254

General Characters.

Specific Characters.

Name of

Species.

"Silicate*.

are

Ilvaite and Allauite B. B. ntuuiesces slightly when fused decomposed by HC1, and icidedl globule is decidedly magnetic. silica upon yield gelatinous
"

The

Ivaite.

(Lievrite.)

evaporation. Neptunite be soluble in HC1, but may tested for a silicate as directed

is in-

on p. 110, 4. These silicates have a U.B. and pitchy or resinous luster, as well as others which

The B. Intumesces strongly when fused B. Gives reactions globule is sometimes magnetic.
for the rare-earth metals (p. 65).

Allanite.

they, are black owing to the presence of iron, are more proper!} secclassified in subsequent the B. B. to a black globule and colors tions under minerals without Fuses tested Neptunite. flame yellow. Reacts for titanium when metallic luster. 2. as directed on p. 127, |^" Compare Melanotekite, Kenof this trolite, and Braunite,
division.

Fuse with Imparts to the Na 2 CO 3 bead in O. F. a green WOLFRAMITE. Contain tungsten. Fused on charcoal with a Compare hiibnt color (manganese). ]<ra 2 COs, pulverize the fusion, ite, p. 283. mass. and little Na 2 CO 3 yields a magnetic digest with boiling water,
filter.

The

filtrate

made

acid

with HC1 and boiled with tin assumes a blue color (p. 129 Contains little or no manganese. 4 2). to a magnetic mass. The high specific gravity is
noticeable.

Fusible B.

Wolframite, in par

Reinite.

Contain

niobium.

Fused with
in

* . UU UBUCMJJ also [Or I/TV ft ieacts for iron and usually uaovy 1 tested as directed above for wolframite. when + ctf>c\ n Hlrftftted abo
*.
i

COLUMBITE.
Samarskite.

borax, then dissolved and boiled with tin, the solufor tion nssumes a blue color (p. React
99,
'

HC1

uranium and the

on

rare-earth
p. 129,
2,

metals

1).

when
65.

tested as directed

and p
Aannerodite.
(Onnerodite.)

The

high

specific

gravity

is

noticeable.

CUPRITE. or Characterized by Contain copper. ~B. B. alone, streak (see p. 263). with Na a CO 3 on charcoal, give Tenorite. Aftei a globule of copper. (Melaconite.) i moistening with HC1 impar Tenorite crystallizes -in scales; paramelaconite and green colors t( azure-blue Paramelaconite. prisms. the blowpipe flame (p. 72, 1) tube yields tusiDie When heated in the closed as directed on Plattnerite. lead oxide and oxygen gas. Test Contains lead. With Na 2 CO 3 OD 1. of th p. 100, charcoal gives globules metal and a coating of lea to the borax bead Kentrolite. Imparts a reddish-violet color
its
,

sub-metallic luster and re

oxide.

in O. F. (manganese).

Compare

Melanotetote.

The
Contain manganese, but do not

in HCK fine powder is slowly silica o: Yields a small amount of gelatinous

soluble

Braunite.

of the foreevaporation. give the reactions to the roing sections. Impart of antimony reddish- Gives a slight coating of oxide borax bead in O. F. a heated with Na a CO 3 on charcoal. Tiolet color.

when

Laangbanite.
(Longbanite.)

OR SUB-METALLIC LUSTER,
or Easily Volatile.
oncluded.

254

Composition.

(Page 255.)
I.

MINERALS WITH METALLIC OR SUB-METALLIC LUSTER.

B.

Infusible or Fusible above 5,

DIVISION
1.

and Non- volatile.

Iron Compounds.

255

I.

MINERALS WITH METALL:

B.

Infusible, or Fusible

DIVISION

1.

Iro'n

Compounds.

Strongly attracted by a magnet after being heated befor

N.B.
slowly.

The minerals in this division are chiefly the oxides and hydroxides of iron. Several of t: The solutions, after dilution with water, may be tested for ferrous and ferric iron with pc
Specific Characters.

General Characters.

Name

of Species.

Strongly magnetic without heating.

Wheii treated as directed on p. 97, 4, meteoric! lr iron has always, and terrestrial irons have often,;
reacted for nickel.

jj'eteoric

Iron

Malleable.
(p. 257).

Compare platinum

Characterized by containing

much
2).

nickel.

Awaruite.

Very slowly attacked by HC1.

Reacts for titanium
Strongly magnetic without heat
ing.
Brittle.
(p. 127,

ILMENITE

(Titan Iron, in part.)

The

powder is slowly, but completely, soluThe solution reacts for both fer- MAGNETITE. rous and ferric iron. Fus. = 5-5.5.
fine

ble in HC1.

Reacts for magnesium

p. 91,
1. b.

when

tested as directed on
Magnesioferrite.

Gives a coating of oxide of antimony when fused Derbylite. Contains titanium. After fusion with Na a CO 3 on charcoal. with NaaCOs the material can ILMENITE. be dissolved by HC1, and ttie (Titanic Iron.) solution when boiled with tin Distinguished by differences in crystallization and physical properties. becomes violet (p. 127, 2). Pseudobrookite.
Gives a coating of oxide of zinc when the very fine powder, mixed with a little Na 2 CO s is FRANKLINITE. heated intensely on charcoal. Contain manganese. Impart to the Na 2 CO 3 bead in O. F. a Gives a coating of oxide of antimony when treated Melanostibian. as above. green or bluish-green color.
,

Does not give the foregoing

reactions.

Jacobsite.

Water about
ly

5$.

when healed

in the closed tube.

Generally decrepitates violent- Turgite

(Hydro-hematite
in

Give water in the closed tube.

Difficultly
fusible.

Water about
prisms.

Generally crystallized
15$.

Fus.

GOETHITE.
LIMONITE.
(Brown -Hematit

5-55.

Water about
(p. 222).

Mammillary and

stalactitic

Often impure.

Distinct crystals un-

known.
Give
or no water in the Streak

(Indian-red, red-ocher). little Sometimes slightly magnetic before heating. HEMATITE. closed tube. (Specular Iron.) Fus. 5-5.5. Daubreelite reacts for sulphur when roasted in an open tube. Imparts a green color to the salt-of-phosphorus Daubr6elite. bead (chromium}. Compare Cliro'mi'e (p 256). (Meteoric only.) E3g*Compare Tripuhyite (p. 263).

brownish-red

OR SUB-METALLIC LUSTER.
x>ve
ie

255

5,

and Non-volatile.
test

blowpipe in the reducing flame (the

must not be made while the fragment

is

hot, p. 84,

1).

ii

are important as ores of the metal. Generally they dissolve in hydrochloric acid, though often sium ferri- and f errocyanides, as directed on pi 85, 4.

Composition.

(Page 256.)

I.

MINERALS WITH METALLIC OE SUB-METALLIC LUSTER.

B.

Infusible, or Fusible above 5,

DIVISION
2.

and Non-volatile.

Manganese Compounds.
in part.

DIVISION

3,

S56

I.

MINERALS WITH METALLL

B.
Infusible, or Fusible

material will impar trifling quantity of the DIVISION 2 flame is also a to the sodium-carbonate bead in the oxidizing which manganese compounds impart oxidts of manganese. They dissolve in hydrc minerals in this division are chiefly

-Manganese Compomids.-A

N.B.-The

heated in a closed tube

(p. 100,

1).

General Characters.

OR SUB-METALLIC LUSTER.
>ove 5,

256

and Non-volatile.
The green
color

the borax bead in the oxidizing flume a reddish-violet or amethystine color. y delicate and decisive test.
oric acid

with evolution of chlorine gas

(p.

101,

2),

and many of them yield oxygen gas when

Composition

(Page 257.)

I.

MINEEALS WITH METALLIC OK SUB-METALLIC LUSTER

B.
Infusible, or Fusible above 5,
DIVISION
3,

and Non-volatile.

concluded.

1.

MINERALS WITH METALI

B.
Infusible, or Fusibl
DIVISION

General Characters.

Specific Characters.

Name of

Species

After the violet color of titanium has been ob taiued, by continued boiliug with tin the solu tiou finally assumes a blue color (niobium, p Dysanalyte.

ISPCompare

Compare Polymignite, below. Contain titanium. Fused with Fused with the acid sulphate of potash and borax, then dissolved in HC1 and boiled with tin, the solu- fluorspar mixture, momentarily colors the flame Warwickite. green (boron). Fus. = 5.5 tion becomes violet (p. 127, 2). A little of the fine powder mixed with an equa ILMENITE. Variet ( Magn esian volume of Na CO and fused in char
Rulile, OctaJiedrite,
2
3

and Brookite (p. 299), which sometimes are black and have a sub-metallic luster.

coal gives a mass net (see p. 255).

which

is

intensely attracted by a

mag

Pseudobrookite.
Perovskite. (Perofskite.)

After fusing with Na 2 CO 3 and dissolving in HC1 the titanium may be precipitated by ammonia. In the filtrate calcium may be detected by ammonium oxalate, and magnesium by sodium phosphate.

leikielite.

Contain niobium. Fused with borax, then dissolved in renerally imparts to the Na 2 CO 3 bead in O. F. a COLUMBITE. and boiled with tin, the solugreen color (manganese). Fused on charcoal tion assumes a blue color (p. with a. little Na 2 CO 3 yields a magnetic mass. The high specific For variations in specific 99, | 1). Mossite. gravity see p. 7.
gravity is noticeable.

Compare
fusible

the

difficultly

niobium minerals on p. In making the reduction test with zinc the 254,. and those with resinous violet color of titanium appears before the blue to sub-metallic luster on pp. of niobium (p. 99, 2). 298 and 300.

'olymignite.

rantalite. Contain tantalum (p. 123), but React for iron and sometimes, also, for manganese when te&ted as directed above for columor only slight, reacgive no, bite. ?apiolite. tions for niobium. Characterized by exceptionally high Gi-ive reactions for tin and uranium when tested specific gravity. Hielmite. as directed on pp. 126, 2. 3, and 129,

Contains uranium. Imparts to the salt of phosphorus bead Soluble in dilute H 2 S0 4 with the slight evolution of a gas (helium). The high specific gravity is Jraniniie. in O. F. a yellowish-green and noticeable. Pitch Blende.) in R. F. a green color.

Compare

Baddeleyite,

ZrO 2

(p.

3addeleyite.

Gives sulphur dioxide

tube,
fl^g*

when

Compare

roasted in the open Laurite.

Sperrylite, p. 247.

B. B. unaltered. Sometimes mag Contain platinum or the metals Malleable, 'latinum. netic. of the platinum group (pp. 103 and 104). These minerals are Malleable. Loses its tarnish when heated B. B. characterized by exceptionally in R. F., but regains it by heating in the open Palladium. high specific gravities, and by tube.
their insolubility in acid.

any

single Slightly malleable to brittle. Heated in the open tube gives the odor of osmium oxide.

ridosmine.
ridium.

Does not react for osmium.

OR SUB-METALLIC LUSTER,
oo ve 5,

25?

and Non-volatile.

-Concluded.

Composition.

(Page 258.)

II.

MINERALS WITHOUT METALLIC LUSTER,

A.
Easily Volatile or Combustible.

II.

MINERALS WITHO
A.
Easily Volati

The few minerals

are included in this section entirely

Burns with

K,*-~

Knd The sublimate

of sul-

dark in the closed tube is a red to solid

SULPHUR.
orandite.

odor gives the strong phur dioxide.

Contain arsenic.

yellow liquid

when

cold

Yield the volsublimate ol atile, crystalline in arsenious oxide when heated

the

green color to the blowpipe

flame (thallium).

transparent solid mirror obtained by mixing oy may be of arsenious the mineral with six volumes yield tbew hite crystalline sublimate Volatile tube. Na 2 CO 3 and a little oxi(}e when heated in a closed "filCP \/L of Vi.lJ' i ^**^^^ dry _j ,,^ l^rtir%n-i -Li. n S\W\S*-*T t f\ with only a slight tendency to fuse. charcoal powder and heating 1 in a closed tube (p. 51.
carefully ).

"s?.B^^^AS^^AS&
"
An arsenical
when
cold.
5

EALGAR.
RP1MENT.
rsenolite.

4-

^-1

laudetite.

Contain antimony.

dioxide. In the open tube gives sulphur B. B. on

<ermesite.

charcoal fuse and coat the Senarmoniiie. heated in the closed tube, and coal with a dense white subli- Fuse easily when oftei Hve a slight white sublimate consisting of the oxides of antimate Valentinite. of Sb 2 O 3 of prisms and octahedrons mony.
.

solution the Volatile without (,,-ion Sal-ammoniac. tt//fr/ c/v^vw*'* UllUllll Contaia amm oniu -Give silver nitrate. with Jhe ^ueous odor of ammonia when heated gives a precipitate with lime (igin a closed tube a The aqueous solution gives a precipi Mascagnite. nited calcite), or boiled in Fusible. with potassium test - tube tate with barium chloride. hydroxide. and mercur Streak red. Gives sulphur dioxide Gives a blac CINNABAR. tube (p. 94, 2). in the

-" -

open tube. sublimate (HgS) in the closed Contain mercury. Give a subliwhen heated After testing for the mercury with Isa 2 CO 3 th mate of mercury in wate in a closed tube with dry Calomel. contents of the tube, when dissolved will give a precipitate with silve sodium carbonate (p. 94, 1). 3 and
,

HN0

nitrate.

water, On cooling, the Contains lead. Gives a globule * Quite soluble in hot f of the metal and a coating o solution deposits lead chloride oxide when fused with Na 2 CO on charcoal. an alkaContain sodium or potassium. After ignition B. B. the residue imparts Color the blowpipe flame yel line reaction to turmeric paper.

Cotunnite.

A number o
will

be

fo\

low or

violet, respectively.

METALLIC LUSTER.
or Combustible.

258

larcoal.
.,
,

Composition.

(Page 259.)
II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART

I.

Give a metallic globule when fused with sodium carbonate on

charcoal.

DIVISION
DIVISION

1.

Silver
Ijcucl

Com pounds.
Compounds,
in part.

2.

II.

MINERALS WITHOU n
15,
and Non-volatile.
fu

*59
B.

Fusible from
I.

PART
DIVISION l.-Silver brittle. globule will be

Give a metallic globule when

is

Compounds.-A globule

of silver

obtained by fusing on charcoal

General Characters.

Specific Characters.

Name

of Species.

an roustite. When heated in the closed tube readily yield (Ruby Silver.) Contain sulphur. Heated in the abundant sublimate of sulphide of arsenic, deep tube yield sulphur direddish-yellow Xanthoconite. when hot, open red, almost black oxide and the oxides of either when cold (p. 140), and beyond this a slight (Rittingerite.) arsenic or antimony. in onifrmvu. sublimate of sulphur.
If the globule obtained with ing on charcoal
is brittle, it

PUUIllUalO by heat in NaaCO, Upon intense and prolonged heating

converted to pure silver by heating O. F. with borax. Compare Miargyrite and

may be

ed the closet of anti tube a slight sublimate of oxysulphide hot. mony deposits where the glass is verywhen This is black when hot, reddish-brown it there is a slight cold 3), and beyond 45,
(p.

'y

rangy rite. (Dark-red Silver Ort

Pyrostilpnite. (Fireblende.)

Polybasite

(p. 250).

deposit of sulphur.

The sublimate

both (lead chloride) is white,

when

Cerargyrite.

hot and cold.

bromine, o Sublimates of thecM0 iodine. leaC ride, bromide, or iodide of are obtained by heating will tube as di galena in a closed 4. reeled on p. 68, The chloride and bromide ar seclile and can be cut with knife like horn.
chlorine,

(Horn

Silver.)

Contain

The sublimate (lead bromide) is sulphur-yellow when hot, but white when cold. The chlorine
in 69,

Embolite.

embolite may be detected as directed on p

5.

Bromyrite.
Miersite.

The sublimate (lead iodide) is dark orange-re( when hot, lemon-yellow when cold. Cupro its reaction iodargyrite may be identified by
for copper.

lodyrite.

lodobromite.

Cuproiodargyrite.

DIVISION 2

-Lead Compounds.- Globules of lead and

but the globules of bismuth gives a very similar reaction, should be used, 3 to 2 of water) lead minerals dilute nitric acid (1 part
are brittle.

a yellow coating of lead oxide are The pale azure-blue flame

HNO

and

in the solutior

N.B.-The

with the exception of those cor various salts of lead will be found in this division,

Soluble in warm Carbonates. acids with evolution dilute of carbon dioxide (effervescence). Generally it is best to employ but for Lead8 dilute hillite use dilute HC1.

HNO

METALLIC LUSTER.
only Slowly or Partially Volatile.
with sodium carbonate on charcoal.
h sodium carbonate.

259

When

antimony

is

present,

some

of

it -will

alloy with the silver

and the

Composition.

(Page 260.)

II.

MINERALS WITHOUT METALLIC LUSTEK.

Volatile.

B.

Fusible from 1-5, and Non- volatile, or only Slowly or Partially

PART

I.

Give a metallic globule when fused with sodium carbonate on

charcoal.
DIVISION
2.

Lead Compounds,

continued

II.

MINERALS WITHOl

260
B.

Fusible from
I.

15,

and Non-volatil

PART

Give a metallic globule when

DIVISION
2.

Lead Cc
Species.

Cetera! Characters.

Specific Characters.

Name of
narite.

Sulphates.

When mixed
a
little

Nu a CC and
3

charcoal

The HC1 solu-" in the closed tube. with Give water is added tion gives a blue color when ammonia
in excess.

ledonite.

in R. F. on powder, and fused

soda flame. a sodium sulphide is obtained B. B. gives strong a moistened which blackens Reacts Gives much water in the closed tube. 2). silver surface (p. 122, for ferric iron, and a phosphate or arsenate. ~ is rather soluble The fine powder Compare Lossenite, beyond. The soin boiling dilute HC1. on cooling deposits lead lution
chloride, and, after filtering,
it

charcoal,

a mass containing

aracolite.

eudantite.

NGLESITE.
anarkite.

chloride a gives with barium precipitate of barium sulphate.

Phosphates.
dilute
A.

ive

none of the above

reactions.

few drops of the

solution,

HNOs
to

when

added

ammonium molyb-

date, give a yellow precipitate 1). (p. 103, the Arsenutes, be-

B. B. in a closed tube distinctly crystalline. of lead chloride. gives a slight sublimate a green color to the salt of phosphoru inparts bead in O. F. (chromium^
Jives

a globule usible B. B. alone on charcoal to becomes which, on slow cooling, generally YROMORPHITE.

auqueliuite.

(Laxrnaunite.)

Compare

low.

much water

in the closed tube.

lumbogummite.

with silver nitrat 3 solution gives a precipitate of silver chloride. ;3f~Compare Endlichite, below.
he dilute
Arsenates.

HNO

Mimetite.

Ecdemite.
Jarminite.

fragment of the
use B. B. to a magnetic mass. 1). for a sulphate (p. 122,

mineral when placed in a closed tube with a few splin ters of charcoal, and heated in of tensely B. B., gives a deposit
arsenic (p. 51,
1,

Lossenite react
jossenite.

a).

The

HNO

solution

is

rendered blue by

ammoni
Bayldonite.
Caryinite.

to the Na a CO 8 bea mparts a bluish-green color in O. F. (manganese). solution gives with silv 3 The dilute nitrate a precipitate of silver chloride. Endlichite is a variety containing a little arsenic

(copper}

HNO

Vanadinite. (Endlichite.)

Psittacinite.

The
Vanadates.

HNO

solution

is

rendered blue by additio

Cuprodescloizite
Cuprodescloizite.

Impart to the salt o F. phosphorus bead in O. cole yellow to deep amber which in R. F. is changed t
green.

of

ammonia

(copper).

mineral. variety of the following

Gives water in the closed tube.

Reacts for zinc

Descloizite.

Gives water in the closed tube. zinc nor copper.

Contains neither
|

Bl ackebuschite
.

OIVIBION

2.

Lead Compounds.

Continued on next page.

METALLIC LUSTER.
Dr

260

Volatile. only Slowly or Partially

ed with sodium carbonate on charcoal.

ijbuiids.
Continued.

Composition.

(Page 261.)

II.

MINERALS WITHOUT METALLIC LUSTER.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

Volatile.

PART

I.

Give a metallic globule when fused with sodium carbonate on

charcoal.

DIVISION

2.

Lead Compounds,

continued.

II.

261
B.

MINERALS WITHO
15, and
DIVISION

Fusible from
I.

Non-volati

PART

Give a metallic globule whei

2.

Lead C

General Characters.

[?'

METALLIC LUSTER,
sodium carbonate on charcoal.
Continued.

261

or only Slowly or Partially Volatile.

Jsed with
>

pounds.

Composition.

(Page 262.)

II.

MINERALS WITHOUT METALLIC LUSTEK.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART

I.

Give a metallic globule when fused with sodium carbonate on

charcoal.

DIVISION 2

Lead Compounds,

concluded.

DIVISION

3.

Bismuth Compounds.

262
B.

II.

MINERALS WITHOI
15, and
DIVISION

Fusible from
I.

Non-volati

PART

Give a metallic globule when

2.

Lead C<
of Species.

General Characters.

Specific Characters.

Name

Silicates.

2). Jives the reaction for sulphur (p. 122, "be only mineral containing the sulphite radical. _ * ertils are readily decomposed 3 aud yield gelatinous by in physical proper Barysilite. Mela- Distinguished by differences silica upon evaporation. 9$ ties and by the presence of calcium (CaO Kentrolite are notekite and Qanoinalite. in Ganonmlite. but best decomposed by HC1, too little silica to give contain bead, Melanotekite. a good jelly. They leave a B. B. in R. F. fuses to a magnetic residue of silica, however, when dish- violet color to the borax bead a red the HC1 solution is evaporatec Imparts Soluble in HC1 with Kentrolite. in O. F. (manganese). to dryuess and then treatec evolution of chlorine. is with acid. Hyalotekite and borou 3 insoluble in acids, but may^bt Hyalotekite. 4 tested as directed on p. 110,

The

three

first

mm-

HNO

>

The

Do not give the reac Oxides. tions of the foregoing minerals

Plattnerite. colors of the different minerals are very Phutnerite and Minium give in the closed tube Minium. oxygen gas when heated and leave readily fusible lead 100

characteristic.

(p

1)

oxide (PbO).

Massicot.

ffto&tdw of bismuth which are brittle and a yellou on charcoal with a mixture of potassium iodide and sulphur (p. red sublimate obtained by heating

DIVISION 3

-Bismuth Compounds.

Dissolve in HC1 Carbonates. with evolution of carbon dioxide (effervescence).

n the closed tube gives little or no water.

Bismutosphserite.
Jismutite.

n the closed tube gives water.

Contains chlorine.
nitrate a chloride.

The

dilute

HNOs solution gives with silver In

precipitate of silver

the closed tube gives water.

Daubreeite.

'

Silicates.

Soluble in HC1, and silica upon Distinguished yield gelatinous evaporation.

Eulytite.

by

differences in crystallization.
Agricolite.

Vanadate. Imparts to the sal of phosphorus bead in O. F. a Soluble in HC1. yellow and in R. F. a green
color.

Pucherite.

bead in R. Imparts to the salt of phosphorus Walpurgite. Arsenates. fragment of thi a green color (uranium). mineral when placed in Atelestite. closed tube with a few splin ters of charcoal, and heate< React water. only for arsenic, bismuth and intensely B. B., gives a deposit Atelesite decrepitates. of arsenic (p. 51, 1, a). Mixite \\J. ~ut/. JUtMtiiG (p. 264). V^uiupaic ^Jjff When mixed with Na,CO, and charcoal powder and heated in a closed Tellurate. with water, yields a Montanite. tube, sodium telluride is formed, which, when treated reddiflh-violet solution (p. 124).

METALLIC LUSTER,
or only Slowly or Partially Volatile.
;ed

with sodium carbonate on charcoal,

Concluded.

pounds.

Composition.

(Page 263.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Won- volatile, or only Slowly or Partially

PART

I.

Give a metallic globule when fused with sodium carbonate on

charcoal.
DIVISION
4.

Antimony Compounds.
Copper Compounds,
in part.

DIVISION

5.

II.

MINERALS WITHOI

and Non-volatil B.-Fusible from 1-5,

PAET

I.

Give a metallic globule when

which

4.-Antimony
General Characters.

Compounds.-^^ of antimony
Specific Characters.
_

F^d^iUr^CoTu^n boiled with

with

treated
tin,

a violet the solution assumes *). color (titanium, p. 127. fe

HC1 and

ww Compare

Mauzeliite,

for lead. gives a reaction RM.

DerbyUte

(p.

Lewisite.

mass. B. B. fuses to a magnetic

Gives no reaction for titanium

sla B. B. fuses to a dark non-magnetic

K.B.-H-* a,l of the .iuevals containing copper

wU
UPRITE.
(Ruby Copper.)

reaction tor

MALACHITE.
Soluble in HC1 Give water in the closed tube. Carbonates. their color. with evolution of carbon diguished by
oxide (effervescence).

Readily distin

AZURITE.
with
Spangolite.
Connellite.

_
The HC1
solution gives a slight precipitate barium chloride (sulphate). (p. Spangolite exhibits pyro-electricity

to th Contain chlorine. Impart blowpipe flame an azure-blu moist color without previous nitrat ening with HC1. Silver

Nantokite.

gives a chloride dilute

when added
3

precipitate

of

silve

to th

Atacamiie.

UNO

solution.

tube. Give acid water in the closed

Footeite.

in a close Colors th Heated with potassium bisulphate Contains iodine. tube gives vapors of iodine. intense green blowpipe flame Continued on next page.

Marshite.

5.-Copper Compounds.

263

METALLIC LUSTER,
Volatile. or only Slowly or Partially

on charcoal. ed with sodium carbonate

CO aUn9 of

carbonate. B. B. on charcoal with sodium anUinony o*ie, are obtained by fusing

Composition.

(Page 264.)

II.

MINERALS WITHOUT METALLIC LUSTER.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

Volatile.

PART

I.

Give a metallic globule when fused with sodium carbonate on

charcoal.

DIVISION

5.

Copper Compounds,

continued.

II.

MINERALS WITIK
15, and Non-vola

B.

Fusible from
I.

PAKT

Give a metallic globule wher

DIVISION
5.

Coppe

METALLIC LUSTER.
ilj

264

or only Slowly or Partially Volatile,

lied with

sodium carbonate on charcoal.

Continued.

Compounds.
Composition.

(Page 265.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

fusible from 1-5, and Non- volatile, or only Slowly or Partially

PART

I.

Give a metallic globule when fused with sodium carbonate on

charcoal.

DIVISION

5.

Copper Compounds,

concluded.

II.

MINERALS WITHOUT 15,

and Non-volatile,
fui

B.

Fusible from
i,

p ABT

Give a metallic globule when

DIVISION
5.

Copper C
of Species.

General Characters.

Specific Characters.

Name
tiie

Decrepitates violently
tube.

when

heated in

closed
Chalcophyllite.

Arsenates,

When concluded. in a B heated intensely B. B. l closed tube with a few

tprs of charcoal, ters

After

^^
Jf

using

B
'

B,

in the forceps the

crystalline.

globule Euchroite conloses

""*

ivenite.

**

most of these

"auiij
1, b).

an ble ones) are reduced and arsenical mirror is formed (p. When the foregoing 51 a). treatment does not yield a satisfactory result, the method
"

fusiminerals (all of the easily

tube , !ke gypsum (p 82 ose . faint water at a fain Euchroite. Oliviuite gives a little
riuite.

of 'crystoUtoion, and

i IL

red heat.
in dis-

given on p. 51,
used.

<?,

may

As these minerals have not been observed ol Cornwallite. tinct crystals, a quantitative determination lor some of their constituents may be necessary o be Erinite contains 5 percent
identification.

water, Cornwallite Trichalcite 16.

8,

Leucochalcite 10, and

eucochalcite.

Trichalcite.

Fuses B. B. on charcoal to Reacts for ferric iron (p. 85, 4). bead in R. Imparts to the salt of phosphorus a ffreen color (uranium).
Phosphates.-A. little
solution
of the

a magnetic mass

Chalcosiderite.

Torbernite.

(Uran-mica.)
Libethenite.

HNO
Distinguished by differences and physical properties.
in
crystallizatio

when added to ammo

Dihydrite.
1).

nium raolybdate gives a yellow

precipitate (p. 102,

Pseudomalachite.

Calciovolborthite.
tes Vanadates

on p. 13 for vanadium when treated as directed o 34 per cent of water. Calciovolborthite contains 5 and Volborthite

-ve e reacon -Give the reaction

Volborthite.

i._ Decomposed by

a yellow residue of boiling HC1, leaving

i

Cuprotungstite.

the volatile subli

for th

water aud a less volatile, liquid 'd tube a and testjchalcomenite. obtained. Break off the end of the tube _^ flame coloration as directed on p. 107.
little

ETALLIC LUSTER.
Volatile. only Slowly or Partially

265

with sodium carbonate on charcoal.

poimds.

Concluded.

Composition.

(Page 266.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART

II.

Become magnetic

after heating before the blowpipe in the reducing flame.

DIVISION

1.

Soluble iu hydrochloric or nitric acid without a perceptible residue and without yielding gelatinous silica upon evaporation.

266
B.

II.

MINERALS WITHC
5,

Fusible from 1

and Non-volati

PAKT
DIVISION
1.

II.

Become magnetic

after heating before the blowp;

Soluble in hydrochloric or nitric acid without a perceptible residue and without

see Part III, Division 2, p. 275.

General Characters.

METALLIC LUSTER.
or only Slowly or Partially Volatile.

266

n the reducing

flame.

Iron, Cobalt

and Nickel Compounds.

For
details concerning the

ing gelatinous silica

upon evaporation.

method of making

this test,

Composition.

(Page 267.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART

II.

Become magnetic

after heating before the blowpipe in the reducing flame.

1,

DIVISION

continued

II.

MINERALS WITHO

and Non-volati B.-Fusible from 1-5,

PART IL-Become magnetic

after heating before the blowpi

DIVISION

General Characters.

Specific Characters.

Name

of Species.

a when placed Yield an arsenical mirror of charcoal and closed tube with a fragment (p. 51, $a). heated intensely before the blowpipe

Lossenite.

Barium Sulphates, concluded. to th* chloride when added dilute HC1 solution gives of barium sulphate
precipitate

Castanite.

Copiapite.

Utahite.

Whenheald'in

the closed tube and gener give acid water, of sulphur di Illy, the odor the en. oxide is perceptible at of the tube. not for React tor ferric iron but when tested as directed
ferrous,

Amarantite.

a *" 01 Cyprusite, which contains Kcept in the case of uyutw*, wTrnn iron these minerals have only ittle aluminium, the closed tube When heated the base

rsidTof firrie*** mark

crushed, gives a red

^Mf ^"U
1'

broferrite .

(red-ocner;.

Insoluble, 'or only partially uble, in cold water.

sol

Carphosiderite.

Glockerite.

Cyprusite.

iGive a blue color to The HC1 solution has a rose color.

'

the borax bead

.

(cobalt).

When heated Arsenates. tensely B. B. in a closed with a fragment of charcoal th arsenate is reduced and a_ arsenical mirror is formed (p.
51,
a).

cient

contains sumAnnabergite below sometimes to cobalt to give a blue color

'

om.

A iic

^^

is green coior. Cabrerite lergite containing magnesium

n solutions have a a variety of anna- Cabrerite

V iwiv/u

Pharmacosiderit

Provided the mineral contains much calcium it is best to heat in a closed tube with Na 2 CO 8 and charcoal-dust, as directed on p. 51, 6.
Arseniosiderite.

DIVISION

1.

Concluded on next page.

'

METALLIC LUSTER
Cobalt and Niclcel Compos reducing flame.-Iro,

Volatile. or only Slowly or Partially

in the

-Continued.

Composition.

(Page 268.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Won- volatile, or only Slowly or Partially

PART

II.

Become magnetic

after heating before the blowpipe in the reducing flame.

1,

DIVISION

concluded.

II.

MINERALS WITH01

268
Non-volatil B.-Fusible from 1-5, and
after heating before the blowpi

PABT IL-Become magnetic

DIVISION

Name
General Characters.

of Species.

Contain

closed tube. manganese. little or no water in the Impart to the borax 2). bead in O. F. a red- Reacts for fluorine (p. 76, tube (OH iso. w. color. no water in t* dish - violet React f or ferrous iron when the dilute HC1 Gives water in the closed tube solution is tested with
'

F).

potassium ferrocyanide
(p. 85,

g" Compare
phates
of

B. exfoliates the phos- Gives water in the closed tube. B. CMJJj-jg. iron and and afterwards fuses on the edges.
p. 276.

4).

Beg,

manganese on

React for ferrous iron Contain 4). (p. 85,

little

When

in a closed tube, Vivianite gently heated Both darkens. whitens, while Ludlamite

Vivianite.

or

no^manga-

darken on intense

ignition.

Ludlamite.
Chalcosiderite.

nese.

Borickite.

*SbS~
a
.2

added 2 SO 4 is If a drop of dilute of calcium solution, a precipitate trated formed. sulphate will be

to the

conceit

HCU

alcioferrite.

React for ferric iron

arrandite.

fi
*

3 -c ^

>*

the dilute HC1 solution is tested with potassium ferrocyanide(p. 85, 4). All of the minerals in section give this water in the closed

when

Jufrenite.

Beraunite,
(Eleonorite.)

Phosphosiderite.

tube.
base. Contain only iron as the
Strengite.

Koninckite.

Cacoxenite.

iron.

METALLIC LUSTER,
or only

206

Slowly or Partially Volatile.

and n the reducing flame.-/r<m, Cobalt

NicM

Compounds.

Crystalli.

zation.

rthorh.
.

mass.

[onocl.
J.

mass.

[onocl. rismat.

rthorh. Fig. 309, Page 207.

Blue, bluish-

O. 3 (P0 4 ) a .8H a

green

tc

Pear i y to
vit]

Monocl. U. prism.
Vlonocl.

U. tabular
^e,Al) 2 (FeO) 4

(P0 4 )4.8H O.
3

Light to dark green1

__l

y itreou8

Triclinic.
.

Massive.

Reniform
Massive.
Foliated.

pheroidal.

il,Fe)PO 4 .2H 2 0.

green or yel

Radiated^
)rthorh.
J.

Fibrous
foliat.

Vlonocl.

U.

Orthorh.

O rthorh.
U.
cryst.

Radiated.
Radiated.
i '

c,(OH),P04.
4^ilat>.
4.

Uolden-yellow Silky.
Blackish-green nearly black.

;MgB 2

Fe"Fe'" 2 O 4

ul]

silky<

Orthorh. Fibrous.
Massive.

MammilL

(Page 269.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART

II.

Become magnetic

after heating before the blowpipe in the reducing flame.

DIVISION

2.

Soluble in hydrochloric or nitric acid, and give gelatinons silica upon evaporation, or decomposed with the separation of silica.

269
B.

II.

MINERALS WITH01
15, and
Non-volat:

Fusible from

PART
DIVISION
2.

II.

Become magnetic

after heating before the blowpi

this test see Part III, Division 3, p. 278,

Soluble in hydrochloric or nitric acid and give gelatinous silica upon evapoi aud Division 4, p. 281.

General Characters.

METALLIC LUSTER.
or only Slowly or Partially Volatile.
Q the reducing flame.
a,

269

Iron, Cobalt

and Nickel Compounds.

silica.

or decomposed with

the separation of

For

details

concerning the method of making

Composition.

(Page 270.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART

II.

Become magnetic

after heating before the blowpipe in the reducing flame.

DIVISION

3.

Insoluble in, or only slightly acted upon by, acids.

U.
6.
ihisible

MINERALS WITH(
15,
and Non-vola
blowp
or oul

from

PART

II.

Become magnetic

after heating before the

DIVISION

2.

Insohible

in,

General Characters.

T METALLIC LUSTER.
3,

370

or only Slowly or Partially Volatile.

Iron, Cobalt

in the reducing flame.

lightly acted

and Nickel Compounds.

upon by,

acids.

Composition.

(Page 271.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART
ule,

With sodium carbonate on charcoal do not give a metallic globIII. and when fused alone in the reducing flame do not become magnetic.
1.

DIVISION

After intense ignition before the blowpipe, either in the forceps or on charcoal, the ignited material gives an alkaline reaction when placed

on turmeric-paper.
faction a.

Easily and Completely Soluble in Water.

In part.

271
B.

II.

MINERALS WIT]
15, and Ifon-volat
metallic g
t

Fusible from

PART
DIVISION
1.

III.

With sodium carbonate on charcoal do not give a

After intense ignition before the blowpipe, either in the forceps or on chare
Section a.

Easily

and

>

N.B. The minerals in this section are chiefly salts of the alkali metals, sodium and potassium, Flame tests will generally serve to identify the metals, and it is recommended to make the t 1), but only those containing sodium as an essential constituent give an intense and persistc (p. 115, color when viewed through rather dark blue glass (p. 105, 1).
taste.

General Characters.

UT METALLIC LUSTER.
or only Slowly or Partially Volatile.
:le,

2?J

and when fused alone

in the reducing flame do not become magnetic.

reaction

the ignited material gives

vletely soluble

an alkaline

when

placed on moistened turmeric-paper.

in water.

volatile acids (fiydrochloric, carbonic, sulphuric,

p. 35.

on platinum wire as directed on

rellow.

The

violet

and nitric). Most of them have a decided saline Most minerals will impart some 3'ellow color to the flame flame of potassium, which may not be very evident, has a decided purplish-red

Composition.

(Page 272.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non- volatile, or only Slowly or Partially

III. With sodium carbonate on charcoal do not give a metallic glob* and when fused alone in the reducing flame do not become magnetic.
1.

PART
ide,

DIVISION

After intense ignition before the blowpipe, either in the forceps or on charcoal, the ignited material gives an alkaline reaction when placed

on turmeric-paper.
Section a.

Easily and Completely Soluble in Water.

Continued.

II.

MINERALS WITH'
15, and
Non-vola1

B.

Fusible from

PART
DIVISION
1.

III.

With sodium carbonate on charcoal do not give a metallic c After intense ignition before the blowpipe, either in the forceps or on chai
Section a.

Easily

and

com].

General Characters.

T METALLIC LUSTER.
,

273

or only Slowly or Partially Volatile.

wle,
1,

and when fused alone

an

the ignited material gives in water.

in the reducing flame do not become magnetic. alkaline reaction when placed on moistened turmeric-paper.

ly soluble

Continued.

Composition.

(Page 273.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART
ule,

III. With sodium carbonate on charcoal do not give a metallic globand when fused alone in the reducing flame do not become magnetic.
1.

DIVISION

After intense ignition before the blowpipe, either in the forceps or on charcoal, the ignited material gives an alkaline reaction when placed on moistened turmeric-paper.
Easily and completely soluble in water.

Section a.
Section
b.

Concluded.
In part.

Insoluble in water, or difficultly or only partially soluble.

273
B.

II.

MINERALS WITHOU'
15, and
Non-volatile
g\

Fusible from

FABT
DIVISION
1.

III.

With sodium carbonate on charcoal do not

give a metallic

After intense ignition before the blowpipe, either in the forceps or on chare
Section a.

Easily

and

General Characters.

METALLIC LUSTEB.
only Slowly or Partially Volatile.
le,

273

and when fused alone in the reducing flame do not become magnetic
an
alkaline reaction

the ignited material gives

pletely soluble in water.

when

placed on moistened turmeric-paper.

Composition.

(Page 274.)

II.

MINERALS WITHOUT METALLIC LUSTER.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

Volatile.

PART
ule,

III. "With sodium carbonate on charcoal do not give a metallic globand when fused alone in the reducing flame do not become magnetic.
1.

DIVISION

After intense ignition before the blowpipe, either in the forceps or on charcoal, the ignited material gives an alkaline reaction when placed

on moistened turmeric-paper.
Section
b.

Insoluble in water, or difficultly or only partially soluble.

Concluded.

II.

MINERALS WITHC
15,
and Non-vola

274
B.

Fusible from

PART

III.

With sodium carbonate on charcoal do

not give a metallic

or on char before the blowpipe, either in the forceps DIVISION l.-After intent ignition
Section
&.

Insoluble in water, or dijjk

General Characters.

Specific Characters.

Name

of Specie

Ammonia
droxide

S!'

Give
in

much water
the
is

Gives no alone B. B.

of aluminium hy gives a precipitate to the HC1 solution. decided flame coloration when heated

when added

Ettringite.

GYPSUM.
(Alabaster.)

closed

tube.

powder

Gives a yellow flame (sodium). readily soluble in boiling, dilute HC1. Give a violet flame (potassium), seen best througl blue glass. Polyhalite reacts for magnesium
(p. 91,
1).

The

fine

Wattevillite.

Polyhalite.

Syngenite.
Glauberite.

^23
I

Give little or no the in water

closed tube. Glauberite is read
ily,

Gives a yellow flame (sodium).

Gives no decided flame coloration alone B. B.

when

heated
j

ANHYDRITE

si*

and

Anhy
crimson flame (strontium).
CELESTITE.

dritc slowly, sol Gives a uble in boiling

dilute HC1, while Celestite and Ba rite are almost in Gives a yellowish-green flame (barium). soluble.

ARITE. (Heavy Spar.)

of

3W

jj^-

on page Compare the magnesium sulphates may be difficultly soluble in water.

Easily fusible.

212,

some

which

Powdered
Give little or no the in water
closed tube.

cryolite
its

Color the flame yellow (sodium). is scarcely visible in water

refraction.

RYOLITE.

because of

low index of

Gives a reddish flame (calcium}.

231) and decrepitates u iu the closed tube. __________

p horesces

(p.

Give acid water

_
Contains
its

Chiolite.

Often phos when heated FLUORITE. (Fluor Spar.)

.

to a powder the closed tube, Generally decrepitate occun heated in a closed tube. Thomsenohte accom often in very slender in rather stout, and Pachnohte by etch Pachnolite. panied prisms. ing of the glass and a deposit o
fine
silica (p. 77,
5) Occurs as an earthy powder, Compare Pro sodium.

in

whei

fhomsenolite.

n
Gearksutite.

sopite ip. 290).

lodatcs.

Fuse and give iodin

Dietzeite is readily distinguished

by
of

reactio

Lautarite.

vapors
tube.

when heated

in a closet

for chromium with the

salt

phosphoii
Dietzeite.

bead.

METALLIC LUSTER
,

274

or only Slowly or Partially Volatile.

ule,

and when fused alone in the reducing flame do not become magnetic.
when
placed on moistened turmeric-paper.

the ignited material gives an alkaline reaction

or only partially soluble.

Concluded.

Composition.

(Page 275.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Part- ally

PART
ule,

III. With sodium carbonate on charcoal do not give a metallii glob* and when fused alone in the reducing flame do not become magnetic.
2.

DIVISION

Soluble in hydrochloric acid, but do not yield a jelly or a residue of upon evaporation. In part.

sili

275
B.

II.

Fusible from

MINERALS W1THO 15, and Non-volati

not give a metallic g

PART
In order to

III.

With sodium carbonate on charcoal do

DIVISION
2.

Soluble in hydrochloric acid, but do

determine whether a mineral belongs

to this division treat

one or two ivory-spoonfi

until not over 1 cc. remains.

The concentrated
it

or deposits on the sides of the tube,

General Characters.

solution thus obtained should be a clear liquid (no should go wholly into solution upon addition of water and ws

Specific Characters.

Name

of Species.

The dilute HC1 solution gives with barium chloride a precipitate of barium sulpha Sulphates. number of the sulphates of ah. they give a faint and not very decided alkaline reaction. ignition they yield an infusible muss of oxide and will be found, therefore, on subsequent page

rQ

*T3
Q)

Q> OJ

^ ^ V >
g^aooa

ft c^ci c

1*
s

$ .g ,Q y_
05

111

1!
>

Ss-3
^J-S
^ TB^ o x

1S

s^
g^a
t

e^

3** 37; *
'*""
i

J 12 a
**>

s ~

.2

S' 5

!?

= i '~
03

i
J3

2F
|l| ||| ~ ~
^

fcf

'

METALLIC LUSTER.
or only Slowly or Partially Volatile.

275

lie,

and when fused alone

in the reducing flame do not become magnetic.

yield

a jelly or a residue of silica upon evaporation.

material in a test-tube with from 3 to 5 cc. of hydrocloric acid, and ooil from the solution silicate), or, in case any solid material separates

f the finely pulverized

ick
ng.

and gelatinous, indicating a

Composition.

(Page

2?'6.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART
ule,

III. With sodium carbonate on charcoal do not give a metallic globand when fused alone in the reducing flame do not become magnetic.
2.

DIVISION

Soluble in hydrochloric acid, but do not yield a jelly or a residue of silica upon evaporation. Continued.

276
B.

II.

MINERALS WITHC
15, and
Non-volati
give a metallic g

Fusible from

PABT

III.

With sodium carbonate on charcoal do not

DIVISION
2.

Soluble in hydrochloric acid, but do not yie

General Characters.

METALLIC LUSTER,
or only Slowly or Partially Volatile.
le,

276

and when fused alone in the reducing flame do not become magnetic.
y or a residue of silica upon evaporation.
Continued.

Composition.

(Page 277.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PAKT
ule,

With sodium carbonate on charcoal do not give a metallic globIII. and when fused alone in the reducing flame do not become magnetic.
2.

DIVISION

Soluble in hydrochloric acid, but do not yield a jelly or a residue of silica

upon evaporation.

Concluded.

277
B.

II.

MINERALS WITHO
15,
and Non-volati
metallic
g*

Fusible from

PART

III.

With sodium carbonate on charcoal do not give a

DIVISION
2.

Soluble in hydrochloric acid, but do not

General Characters.

METALLIC LUSTER,
or only Slowly or Partially Volatile.
lie,

277

and when fused alone in the reducing flame do not become magnetic,
Concluded.

d a jelly or a residue of silica upon evaporation.

Composition.

(Page 278.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Won- volatile, or only Slowly or Partially

PART
ule,

III. With sodium carbonate on charcoal do not give a metallic globand when fused alone in the reducing flame do not become magnetic.
3.

DIVISION

Soluble in hydrochloric acid, and yield gelatinous silica upon evaporation

Section a.

In

the closed tube give water.

278
B.

II.

MINEKALS WITHO
15, and
Non-vola
,

Fusible from

PAKT

III.

With sodium carbonate on charcoal do

DIVISION
3.

not give a metallic

Soluble in hydrochloric

aci(

gelatinous

to this division treat one or two ivory-spoonfuls In order to determine that a mineral belongs and T mineral should go wholly into solution, unless difficultly soluble, over 1 c c remains. The will not go into solutior The silicic acid thus separated 108, 1). silicic acid
(p.

Section a.

In

the closed tube give water.

Silicat

General Characters.

Specific Characters.

Name

of Specie

B. B. fuses to a clear glass, coloring the flame green. closed tube.

Gives a

little

water in the DATOLITE.

Edingtonite.

The

dilute

HC1

solution gives with

SO 4

a precipitate of barium sulphate.

in O. F.

Imparts a reddish-violet color decidedly micaceous structure.

to the

borax bead

(manganese).

Has a

Ganophyllite.

with difficulty. Gives a coating of oxide of zinc B. B. whitens and fuses when fused on charcoal with a little Na 3 CO s B. B. fuses to a yellow globule.
.

CALAMINE.
Clinohedrite.

B.

B.

swells,

Iruilis

and fuses

to

a vesicular
Cancrinite.

Contain the carbonate radical. A fragment dissolves with

effervescence in

globule. water.

In the closed tube whitens and gives

warm

dilute

HC1

Gives the reactions of the rare-earth metals (p. 65)

Jenosite.

(Kainosite.)

NATROLITE. Contain little or no calcium. Fuses quietly to a clear, transparent glass. After separation of the silica 4), amand alumina (p. 110, Hydronephelite. Fuses easily to a white enamel. monium oxalate produces little or no precipitate in the am- Fuses to a glassy enamel. Gives a reaction for Spadaite. moniacal nitrate (p. 60, G). magnesium (p. 91, Fuses to a voluminous, frothy slag. Exnibits Sc olecite. Contain aluminium and calcium. '_ py roelectricity (p. 231). after In the HC1 solution,
|

separation of the silica

1),

(p. 108,

Mesolite.

cipitate

fhofhsonite. Do not exhibit pyroelectricity. of aluminium globules. hy (Comptonite.) Mesolite contains both the uatrolite and scolecite droxide (p. 42. 2), and in the molecules. oxalate profiltrate ammonium ^evynite. duces a precipitate of calcium with oxalate (p. 60, 6). Usually found in simple prismatic crystals Laumontite. Compare Allaniie (p. 280 oblique terminations. which may contain water if

ammonia produces

a pre- Fuse

with

intumescence

to

white

vesicular

impure. *

Occurs

in

complex, twin

crystals,

resembling Gismondite.
Pectolite.

tetragonal pyramids.
.

Contain little or no aluminium After dissolving in HC1 and

Gives a poor jelly with HC1.

clear glass.

B. B. fuses to a

separating the silica (p. 108, 8 1) the solution gives no, or Fusible to a blebby only a slight, precipitate with

Okenite.

ammonia.

Gyrolite.

C
,

METALLIC LUSTER.
or only Slowly or Partially Volatile.

278

bule,

and when fused alone

silica

in the reducing flame do not become magnetic.

nd yield gelatinous

upon evaporation.

he finely powdered material in a test-tube with from 3-5 c.c. of hydrochloric acid, and boil until not i the volume becomes small the contents of the tube should thicken, owing to the separation of
,ed

with additional water or acid.

radical. lontainiug water of crystallization or the hydroxyl

Composition.

(Page 279.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART
ule,

With sodium carbonate on charcoal do not give a metallic globIII. and when fused alone in the reducing flame do not become magnetic.
3.

DIVISION

Soluble in hydrochloric acid, and yield gelatinous

Section
b.

silica

upon evaporation

In

the closed tube give little or

no water.

In part.

279
B.

II.

MINERALS W1THO

Fusible from

15,

and Non-volat
give a metallic
ai
<

PABT

III.

With sodium carbonate on charcoal do not

DIVISION
Section
3.

Soluble in hydrochloric acid,

b.ln

the closed tube give little or

no water.

Art

General Characters.

METALLIC LUSTER.
or only Slowly or Partially Volatile,

279

mle,

and when fused alone in the reducing flame do not

upon evaporation.
hydroxyl.

"become magnetic.

ield gelatinous silica

*rous silicates, or those containing only a little

Composition.

(Page 280.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART
ule,

III. With sodium carbonate on charcoal do not give a metallic glob and when fused alone in the reducing flame do not become magnetic.
3.

DIVISION

Soluble in hydrochloric acid, and yield gelatinous silica upon evaporation.

Section
b.

In

the closed tube give little or

no water.

Concluded

II.

MINERALS WIT:
15, and Non-volat
give a metallic g

28U
B.

Fusible from

PART

III.

not With sodium carbonate on charcoal do

DIVISION
3.

Soluble in hydrochloric acid,

Section

b.In

the closed tube g\

General Characters.

Specific Characters.

Name

of Species.

uses quietly.

Compare Andradite

(p. 269).

(Meianite.)

Contain titanium.
lution

The HC1
with

sotir

scheffkinite.

when

boiled

'use

assumes a violet color.

After separation of metals the silica, the reactions for the rare-earth may be obtained (p. 65).

with intumescence.

inkite.

Contains niobium.
lution

The HC1 so boiled with tin assumes a blue color (p. 99

when

uc The HC1

to solution imparts an orange color Wohlerite. turmeric- paper (zirconium, p. 133).

Contains zirconium. Gives the Fuses to a yellowish-white enamel. zirconium reaction with tur Ut^P Compare Eudialyte (p. 279). meric-paper (p. 133).
Contains the Tare-earth yttrium (p. 65).

Hiortdahlite.

meta

often glows. B. B. swells, cracks apart, and

Gadolinite.

Very

HC1. easily soluble in yellow flame (sodium).

NEPHELITE. B. B. gives a strong (Nepheline,

lite.)

E18E

Contain aluminium and in som Rather cases also calcium, but do nc

of the fore give the reactions the going divisions. In solution, after separation of the,

in HC1. difficultly soluble color to the blowpipe flame.

Gives

littl

NORTHITE.
(Lime Feldspar.)

HC

ompare The

Feldspars (p. 285).

Sarcolite.

silica

(p.

108,

1),

ammonia
42,

Fuses to a white enamel.

c

alua greenish produces a precipitate of Fuses with slight intumescence to 2)

minium hydroxide

Melilite.

(p.

When

present it may be precipitated in the filGive trate from the aluminium by Fuses with intumescence to a dark slag. means of ammonium oxalate reactions for the rare-earth metals (p. 65).
is

calcium

yellowish glass.

Allanite.

(p. 60,

6).

Fuses with difficulty to a grayish mass.

Gehlenite.

Oives a reaction for magnesium

ufter the separation of silica Difficultly fusible. and calcium (p. 91, 1, 6).

Monticellite.

UT METALLIC LUSTER.
,

280

or only Slowly or Partially Volatile.

ule,

and when fused alone in the reducing flame do not become magnetic.
upon evaporation.

yield gelatinous silica

itlle

or no water.

Concluded.

Composition.

(Page 281.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non- volatile, or only Slowly or Partially

PART
ule,

With sodium carbonate on charcoal do not give a metallic globIII. and when fused alone in the reducing flame do not become magnetic.
4.

DIVISION

Decomposed by hydrochloric acid with

the separation of silica,

but without

the formation of a jelly.

Section a.

In

the closed tube give water.

In part.

28!
B.

II.

MINERALS WITHC
15, and
Non-volata
g\

Fusible from

PART

III.

With sodium carbonate on charcoal do not

DIVISION
4.

give a metallic
acid with

Decomposed by hydrochloric

tf

less than 1 cc. of acid remains.

In order to determine that a mineral belongs in this division treat one or two ivory-spoonfuls c The behavior during this treatment shoukl be carefully observed.

when boiled, however, the liquid becomes translucent, although U decide from appearances whether the insoluble material is separated silica or the undecomposed mil to oxidize any iron that may be present, dilute with 5 cc. of water, boil, and filter, when, if decoo
to the fine, suspended material;

will precipitate aluminium and iron which may be filtered off. In the strongly ammoniacal filtrat while if other bases are present (sodium, potassium and lithium excepted) one or the other of the

for testing for the bases see p. 110, 4. There are some minerals which are slowly attacked by acid* carbonate and sodium phospate; the minerals in this division, however, are readily decomposed by i
Section a.

In

the closed tube give water.

Silicates co

General Characters.

Specific Characters.

Name

of Species.

Structure micaceous. Exfoliates prodigiously when heated B. B. Under the name Vermiculite a number of silicates of aluminium and magnesium are included which have resulted generally from the decomposition or alteration of different Vermiculite. (Jefferisite.) kinds of mica. Their composition cannot be expressed by simple formulas. See The Micas (p. 284).

Fuses quietly to a white enamel. yellow (zirconium, p. 133).

The HC1

solution colors turmeric-paper orange-

METALLIC LUSTER.
>r

281

only Slowly or Partially Volatile.

e,

and when fused alone

in the reducing flame do not become magnetic,

of a jelly.

wation of silica, but without the formation

finely powdered material in a test-tube with

en the powder

mrated
in

silica

from 3 to 5 cc. of hydrochloric acid, and boil until shaken up with the cold acid the liquid will generally appear milky, owing prevents it from becoming perfectly clear. After a little experience one can usually
is first
:

Add a drop of nitric acid in order order to decide definitely, however, proceed as follows ion has taken place, the bases will be in the filtrate. Ammonia, added in excess to the solution, monium carbonate and sodium phosphate will precipitate calcium and magnesium, respectively,
For ents previously mentioned will be very sure to produce a precipitate. give, consequently, slight precipitates of the bases when tests are made with

more complete details ammonia, ammonium

ng water of crystallization or the hydroxyl

radical.

Composition.

(Page 282.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART
ule,

With sodium carbonate on charcoal do not give a metallic globIII. and when fused alone in the reducing flame do not 'become magnetic.
4.

DIVISION

Decomposed by hydrochloric

acid with the separation of silica, but without

the formation of a jelly.

Section a,

In

tlie

closed tube give water.

Concluded.

282
B.

II.

MINERALS WITHOU
15, and

Fusible from

Non-volatile,

PART

III.

With sodium carbonate on charcoal do not

DIVISION
4.

give a metallic gl
acid with
th<

Decomposed by hydrochloric
Section a.

In

the closed

t\

General Characters.

IETALLIC LUSTER,
only Slowly or Partially Volatile.
le,

382

and when fused alone in the reducing flame do not become magnetic,

aration of silica, but without the formation of a jelly.

ive water.

Concluded.

Composition.

(Page 283.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and. Non-volatile, or only Slowly or Partially

PART
ule,

With sodium carbonate on charcoal do not give a metallic globill. and when fused alone in the reducing flame do not become magnetic.
4.

DIVISION

Decomposed by hydrochloric
the formation of a jelly.
Section
b.

acid, with the separation of silica ,

but without

In

the closed tube give little or

no water.
In part.

DIVISION

5.

Insoluble in hydrochloric acid, or only slightly acted upon.

283
B.

Fusible

MINERALS W1THC from 15, and Non-volat:

II.

PART

III.

With sodium carbonate on charcoal do not

DIVISION
4.

give a metallic

(,

Decomposed by hydrochloric
Section
b.

acid, with

In

the closed tube give littl

General Characters.

METALLIC LUSTER,
or only Slowly or Partially Volatile.

283

uh, and
no water.

when

fused alone in the reducing flame do not become magnetic,

silicates.

separation of silica, but without the formation of a jelly.

Anhydrous

Composition.

(Page 284.)

II.

MINERALS WITHOUT METALLIC LUSTER.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

Volatile.

PART
ule,

With sodium carbonate on charcoal do not give a metallic globIII. and when fused alone in the reducing flame do not become magnetic.
5.

DIVISION

Insoluble in 7iydroc?iloric acid, or only slightly acted upon.

Continued.

234
B.

II.

MINERALS \YITHO
15, and Non-volat
not give a metallic g

Fusible from

PART

III.

With sodium carbonate on charcoal do

DIVISION
5.

Insoluble in hydrochloric aci

General Characters.

METALLIC LUSTER
or only Slowly or Partially Volatile.
le,

284

and when fused alone in the reducing flame do not

Continued.

"become magnetic.

only slightly acted upon.

Composition.

(Page 285.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non- volatile, or only Slowly or Partially

PART
ule,

III. With sodium carbonate on charcoal do not give a metallic glob* and when fused alone in the reducing flame do not become magnetic.
Insoluble in hydrochloric acid, or only slightly acted upon.

DIVISION 5

Continued.

285
B.

II.

MINERALS WITHC
15, and
Non-volati
metallic g
c

Fusible from

PART

III.

With sodium carbonate on charcoal do not give a

DIVISION
5.

Insoluble in hydrochloric

General Characters.

METALLIC LUSTER.

or only Slowly or Partially Volatile.

lie,

and when fused alone in the reducing flame do not become magnetic.
Continued.

or only slighly acted upon.

Composition.

(Page 286.)

II.

MINERALS WITHOUT METALLIC LUSTER.

B.

Fusible from 1-5 V and Non-volatile, or only Slowly or Partially

Volatile.

PART
ule,

III. With sodium carbonate on charcoal do not give a metallic glob' and when fused alone in the reducing flame do not become magnetic.
5.

DIVISION

Insoluble in hydrochloric acid, or only slightly acted upon.

Continued.

286
B.

II.

MINERALS WITHO

Fusible from

15,

and Non-volati
give a metallic g

PART

III.

With sodium carbonate on charcoal do not

DIVISION
5.

Insoluble in hydrochloric ac

General Characters.

METALLIC LUSTER,
or only Slowly or Partially Volatile.
ule,

286

and when fused alone in the reducing flame do not become magnetic.
Continued.

or only slightly acted upon.

Composition.

(Page 287.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART
ule,

With sodium carbonate on charcoal do not give a metallic globIII. and when fused alone in the reducing flame do not become magnetic.
5.

DIVISION

Insoluble in hydrochloric acid, or only slightly acted upon.

Continued.

28r
B.

II.

MINERALS WITHC

Fusible from

15, and

Non-volat:

PAR'" III.

With sodium carbonate on charcoal do not

DIVISION
5.

give a metallic g
at

Insoluble in hydrochloric

The remaining
groups.

silicates in this division are

"VPhen crystals are "Ot at

hand

arranged according to their crystallization, because the species in almost all cases may be identified readily bj

General Characters.

METALLIC LUSTER.
or only Slowly or Partially Volatile.
lie,

287

and when fused alone

in the reducing flame do not become magnetic.

Continued.

or only slightly acted upon.

re are
ir

sufficiently pronounced blowpipe characters -which blowpipe and physical properties, as given in the table.

no

may be

used for subdividing them into

Composition.

(Page 288.)

II.

MINERALS WITHOUT METALLIC LUSTER.

Volatile.

B.

Fusible from 1-5, and Non-volatile, or only Slowly or Partially

PART
ule,

III. With sodium carbonate on charcoal do not give a metallic glob* and when fused alone in the reducing flame do not become magnetic.
5.

DIVISION

Insoluble in hydrochloric acid, or only slightly acted upon.

Concluded.

288

II.

MINERALS WITHOU
15, and

B
PABT
III.

Fusible from

Non-volatile

With sodium carbonate on charcoal do not

DIVISION
5.

give a metallic

Insoluble in hydrochloric ac

General Characters.

METALLIC LUSTEK.
r only
tie,

Slowly or Partially Volatile.

and when fused alone in the reducing flame do not become magnetic.
Concluded.

or only slightly acted upon.

Composition.

(Page 289.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.
Infusible or

Very

Difficultly Fusible.

DIVISION

1.

After intense ignition before the blowpipe, either in the forceps or on charcoal, the ignited material gives an alkaline reaction when placed n moistened turmeric-paper. In part.

289

II.

MINERALS WITH01
C.
Infusible or
^

DIVISION

1.

After intense ignition before the blowpipe, either in the forceps or on chare

N.B.

The minerals

in this division are chiefly the salts of the all

General Characters.

METALLIC LUSTER.
y Difficultly Fusible.
the ignited material gives an alkaline reaction

289

when

placed on moistened turmeric-paper.

earth metals, calcium, strontium, and barium, with volatile acids.

Composition.

(Page 290.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.

Infusible or

Very

Difficultly Fusible.

DIVISION

1.

After intense ignition before the blowpipe, either in the forceps or on charcoal, the ignited material gives an alkaline reaction when placed on moistened turmeric-paper. Concluded.
Soluble in Hydrochloric acid, but do not yield a jelly or a residue of silica upon evaporation. In part.

DIVISION

2.

290

II.

MINERALS W1THOV
C.
Infusible or

Ve

DIVISION

1.

After intense ignition before the blowpipe, either in the forceps or on charcoal, th

General Characters.

Composition.

(Page 291.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.
Infusible or

Very

Difficultly Fusible.

DIVISION

2.

Soluble in hydrochloric acid, but do not yield a jelly or a residue of silica upon evaporation. Continued.

2&JL

II.

MINERAL WITH01 LS
C.

Infusible or

Ve
yiel

DIVISION

2.

Soluble in .hydrochloric acid, but do not

General Characters.

METALLIC LUSTEJt.
Difficultly Fusible.
lly

or a residue of silica upon evaporation.

Continued.

Composition.

(Page 292.)

II.

MINERALS WITHOUT METALLIC LUSTEK.

C.

Infusible or

Very
acid,

Difficultly Fusible.

DIVISION 2.-- Soluble in hydrochloric

upon evaporation.

but do not yield a jelly or a residue of silica Continued.

292

II.

MINERALS WITHO
C.

Infusible or Ve:
yie(

DIVISION

2.

Soluble in hydrochloric acid, but do not

General Characters.

METALLIC LUSTER.
Difficultly Fusible.
telly

292

or a residue of silica

upon evaporation.

Continued.

Composition.

(Page 293.)

II.

MINERALS WITHOUT METALLIC LUSTEE.

C.

Infusible or

Very

Difficultly Fusible.

DIVISION

2.

Soluble iu hydrochloric acid, but do not yield a jetty or a residue of silica upon evaporation. Concluded.

293

II.

MINERALS WITHC
C.
Infusible or V<

DIVISION

2.

Soluble in hydrochloric acid, but do not yi

General Characters.

METALLIC LUSTER.
Difficultly Fusible.
elly or

a residue of silica upon evaporation.

Concluded.

Composition.

(Page 294.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.

Infusible or

Very

Difficultly Fusible.

DIVISION

3.

Soluble in hydrochloric acid, and yield gelatinous silica upon evaporation.

294

II.

MINERALS WITHO
C.
Infusible or Ver
Soluble iu hydrochloric acid,

DIVISION

3.

In order to determine that a mineral belongs in this division, treat one or two ivory-spoonfuls o not over 1 cc. remains. The mineral should go wholly into solution, unless difficultly soluble, and
gelatinous
silicic

acid

(p. 108,

1).

The

silicic

acid thus separated will not go into solution

when

he?

General Characters.

Specific Characters.

Name

of Species.

Gives

little

or no water in the closed tube.

iu the closed tube.

WILLEMITE. See
troostite, p. 279.

Contain

Give a coating of oxide of zinc when heated with Gives water a little NftfCOi on charcoal, or
zinc.

Exhibits pyro- CALAMINE.

(Hemimorphite.)

as

shown

in Fig.

49

electricity (p. 231).

(p. 131).

Gives a slight odor of hydrogen sulphide

dissolved in HC1.

when
Danalite.

See p. 269

Contains copper. Gives a globule of copper when fused B. B. IGives water in the closed tube, with Na Q CO 3 on charcoal.

Diopiase.

Rather Contain magnesium. Contains little or no iron. Forsterite. slowly decomposed by HC1. Anhydrous. Treat ivory-spoonful of the Contains a little iron (5 to 15 per finely powdered material in a Anhydrous. cent FeO, rarely more). test-tube with 3 cc. of HC1 Compare HOT- CHRYSOLITE. (Olivine, Peridot.) tonolite (p. 269). to dryuess. and evaporate Then add 3cc. of HC1, a drop! of HNOs, 5 cc. of water, boil Prolectite. and filter. To the filtrate ttdd Give a little water when intensely ignited in a! ammonia to precipitate the, c i ose d tube. Generally give reactions for Chondrodite. iron, filter, and then test the fluorine (p. 76, These closely 2) and iron. filtrate with ammonium oxalate related minerals must be distinguished by Humite. to prove the absence of calcium differences in crystallization, or by means of 6) aud with sodium! a quantitative chemical analysis. (p. 60, Jlinohumite. phosphate to prove the presencel 1, b). of magnesium (p. 91, aluminium. When Contain Yields much treated as directed in the fore- Crumbles when heated B. B. Allophane. water when heated in a closed tube. going paragraph ammonia produces a precipitate of alumin1 1

ium
ed

hydroxide.

Distinguishlittle

by their specific gravity Gives from the heavier minerals iu Fus.

the following section.

or no water

in the

closed

tube.
Gehlenite.

5.

The water is sup- Thorite. Essentially a thorium silicate. (Granite.) P osed to be tbe result of alteration. Contain the rare-earth metals. After separation of the silica Contains the metals of the cerium group. On inthe solution gives the reactions tense ignition in the closed tube gives a little Ceriie. described on pp. 65 and 66. water (hydroxyl). The high specific gravity of Contains the metals of the yttrium group. these minerals is noticeable. B. B. swells, cracks apart, and often glows. Gadolinite. Gives little or no water in the closed tube. Contains uranium. Gives with the salt of phosphorus bead in Gives water in the closed tube. Uranophane. O. F. a yellowish-green and in R. F. a green color.
'

METALLIC LUSTER.
ifficultly Fusible.
yield gelatinous silica
e

29*

upon evaporation.

finely powdered material in a test-tube with from 3 to 5 cc. of hydrochloric acid and boil until n the volume becomes small the contents of the tube should thicken, owing to the separation of with additional water or acid.

Composition.

(Page 295.)

II.

MINERALS WITHOUT METALLIC LUSTER

C. -Infusible or

Very

Difficultly Fusible.

DIVISION

4.

Decomposed by hydrochloric acid with the separation of silica, but without

the formation of a jelly.

295

II.

MINERALS WITHO
C.
Infusible or

Ve
tin

DIVISION

4.

Decomposed by hydrochloric acid with

less

In order to determine that a mineral belongs in this division treat one or two ivory-spoonfuls o than 1 cc. of acid remains. The behavior during this treatment should be carefully observed.

to the fine, suspended material; when boiled, however, the liquid becomes translucent, although th decide from appearances whether the insoluble material is separated silica or the un decomposed min to oxidize any iron that may be present, dilute with 5 cc. of water, boil, and filter, when, if decom

aluminium and iron, which may be filtered off. In the strongly ammoniacal filtrat other bases are present (sodium, potassium, and lithium excepted) one or the other of the for testing for the bases see p. 110, 4. There are some minerals which are slowly attacked by acids carbonate, and sodium phosphate the minerals in this division, however, are readily decomposed lr
will precipitate
if

while

General Characters.

METALLIC LUSTER.
Difficultly Fusible.
iration of silica, but without the formation of a jelly.

295

powdered material in a test-tube with from 3 to 5 cc. of hyurochloric acid and boil until is first shaken up with the cold acid the liquid will generally appear milky, owing )arated silica prevents it from becoming perfectly clear. After a little experience one can usually Add a drop of nitric acid in order ; in order to decide definitely, however, proceed as follows ion has taken place, the bases will be in the filtrate. Ammonia, added in excess to the solution, monium carbonate and sodium phosphate will precipitate calcium and magnesium, respectively, For more complete details ints previously mentioned will be very sure to produce a precipitate.
finely

en the powder

give, consequently, slight precipitates of the bases

Is.

when

tests are

made with, ammonia, ammonium

Composition.

(Page 296.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.
Infusible or

Very

Difficultly Fusible.
Insoluble in hydrochloric acid,

DIVISION

5.

Not belonging

to the foregoing divisions.

or only slightly acted upon.

Section a.

Hardness

less

than that of glass or a good quality of steel.

Can be scratched

by a

knife.

In part.

II.

MINERALS WITHOT
C.
Infusible or

Ver
.

DIVISION

5.

Not belonging
Hardness

to the foregoing divisions.

less

Section a.

than that of glass or a gc

General Characters.

METALLIC LUSTER.
ifficultly Fusible.
uble in hydrochloric acid, or only slightly acted upon.
lality

295

of steel.

Can be scratched by a

knife.

Composition.

(Page 297.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.
Infusible or

Very

Difficultly Fusible.

DIVISION
Section a.

5.

Insoluble in hydrochloric acid, or only slightly acted upon.

less

Hardness

than that of glass or a good quality of by a knife. Continued.

steel.

Can be scratched

297

II.

MINERALS WITH(
C.
Infusible or

V
i

DIVISION
Section a,

5.

Insoluble in hydrochloric, a

Hardness

less tfian that

of glass or a good

General Characters.

T METALLIC LUSTER.
Difficultly Fusible.
or only slightly acted upon.
ity of steel.

297

Continued.
knife.

Can be scratched by a

Continued.

Composition.

(Page 298.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.

Infusible or

Very

Difficultly Fusible.

DIVISION
Section a.

5.

Insoluble in hydrochloric acid, or only slightly acted upon.

less

Hardness

than that of glass or a good quality of steel. by a knife. Concluded.

to

Can be scratched

Section

b.

Hardness equal
knife.

or greater than that of glass.

Can not be scratched by a

In part.

(Page 299.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.

Infusible or

Very

Difficultly Fusible.
acid, or only slightly acted upon.

DIVISION 5.I?isoluble in hydrochloric

Section
b.

Hardness equal

to

or greater than that of glass. Continued. knife.

Can not be scratched by a

299

II.

MINERALS WITIIO
C.
Infusible or V(

DIVISION
Section
6.

5.

Insoluble in hydrochloric ac
to

Hardness equal

or greater than that oj

General Characters.

METALLIC LUSTEK.
Difficultly Fusible.

or only slightly acted upon.

ss.

Continued.
knife.

Can

not be scratched

by a

Continued.

Con .position.

(Page 300.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.
Infusible or

Very

Difficultly Fusible.

DIVISION
Section
b.

5.

Insoluble in hydrochloric acid, or only slightly acted upon.

to

Hardness equal

or greater tlian that of glass. Contin ued. knife.

Can not be scratched by

300

II.

MINERALS WITHO
C.
Infusible or V<
Insoluble in hydrocJiloric ai
to

DIVISION
Section
b.

5.

Hardness equal

or greater than that o

General Characters.

METALLIC LUSTER.
Difficultly Fusible.
Continued.
knife.

300

or only slightly acted upon.

ass.

Can not be scratched by a

Continued.

Composition.

(Page 301.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.

Infusible or

Very

Difficultly Fusiblec

DIVISION
Section
b,

5.

Insoluble in hydrochloric acid, or only slightly acted upon.

to

Hardness equal

or greater than that of glass. Continued. knife.

Can not be scratched by

301

II.

MINERALS WITH01
C.

Infusible or

Ver
ad

DIVISION
Section
b.

5.

Insoluble in hydrocJiloric
to

Hardness equal

or greater than that of

General Characters.

METALLIC LUSTER.
)ifficultly Fusible.
r

SOI

only slightly acted upon.

Continued.
knife.

s.

Can

not be scratched

by a

Continued.

Composition.

(Page 302.)

II.

MINERALS WITHOUT METALLIC LUSTER.

C.

Infusible or

Very

Difficultly Fusible.

DIVISION
Section
b.

5.

Insoluble in hydrochloric acid, or only slightly acted upon.

to

Hardness equal

or greater than that of glass.

knife.

Can not be scratched by

Concluded.

302

II.

MINERALS W1THC
C.
Infusible or Vc

DIVISION
iSeetion b.

5.

Insoluble in hydrochloric
to

Hardness equal

or greater than thai

<

General Characters.

METALLIC LUSTEK.

302

Difficultly Fusible.
,

or only slightly acted upon.

Concluded.
Concluded.

last.

Can

not be scratched

by a

knife.

Composition.

INDEX TO SUBJECT-MATTER.
Acids, 4

Boron, 56
Botryoidal structure, 222 Brachy-dome, 201, 215 Brachy-pinacoid, 201, 215 Bromine, 57 Bulb tubes, 18 Buuseu burner, 13 flame, 31

Acid sulphate of potash, 25

Adamuntiiie luster, 228 Agate mortar, 20 Alcohol-lamp, 15

Aluminium, 42

Ammonia,

reagent, 28

Ammonium,

Ammonium

43 carbonate, 29 hydroxide, 28 molybdate, 29

oxalate, 30 sulphide, 29

Cadmium, 57
Caesium, 58 Calcium, 58 Caudle-flame, 31

Amorphous

sulphocyanate, 30 structure, 221 Antimony, 43 Anvil, 20 Apparatus, 10 Aqua regia, 28 Arsenic, 47 Atomic weight, 5 Atoms, 3 Axes, crystallographic, 159

Carbon, 61
Carbonates, 62 Casseroles, 22

Centimeter scale, 41 Cerium, 64 Charcoal, 16 reactions on, 142 uses of, 39 Chemical affinity, 3
,
,

analyses, 6

composition, calculation of, 5

equations, 5
-

Balances for specific gravity, 234

Barium, 52

principles, 1

Barium

chloride, 30

Chemistry, 3
Chlorine, reactions of, 67 reagent, 27 Chromium, 69
,

hydroxide, 28 Base, hexagonal system, 187 monoclinic system, 210 orthorhombic system, 201 tetragonal system, 179 tricliuic system, 215 Bases, 4 Beakers, 21 Beam Balance, 235 Beryllium, 53 Bismuth, 54 Blowing, 13 Blowpipe, 10 Blowpipe flame, 33 lamps, 14
, , ,

Cleavage, 223 Clino-dpme, 210 Clino-piuacoid, 210 Closed tubes, 18

,

reactions in, 137

Cobalt, 71

Cobalt nitrate, reactions with, 146 reagent, 29 Cohesion, 223 Color, 228 Columbium (see Nicobium), 98
,

Columnar

structure, 221

tips,

11

Bone-asb, 26 Borax, 24
,

Combinations of crystal forms, 166 Combustion, 31

structure, 221 Cotiehoidal fracture, 225 Copper, 71

Compact

reactions with, 148

glass,

25

304
Crystal combinations, 166 form, 163 habit, 165 Crystallization, 155 Cube, 170 Cubic centimeter, 41

INDEX TO SUBJECT-MATTER.
Hexngonal system, 184
Hexakistetrahedron, 175

Hexoctahedron, 172 Holders for platinum wire, 16

HololiL'drul forms, 164 Hydriodic acid, 28

Decrepitation, 34 Definite proportion, law of, 3 Deltoid dodecahedron, 175 Diamond mortar, 19 Didymium, 65 Dimorphism, 8 Diploid, 173 Distorted crystals, 165 Dodecahedron, 170 Domes, mouoclinic, 210

Hydrocarbons, 61 Hydrochloric acid, 27

Hydrochlorplatinic acid, 28

Hydrogen, 81 Hydrogen, sulphide, 27

Hyilroxyl, 81

Inch

scale,

41

Indices, 161

Indium, 82
Iodine, 82 Iridium, 104
Iron, 83

orthorhombic, 200 triciiuic, 215 Droppiug-bottle, 23 Dropping-bulb, 23

,

Isometric system, 169

Isomorphism, 7 Ivory spoon, 21, 41

Jolly Balance, 234

Earthy structure, 221

Elements, 3 Erbium, 65

Lamps, 13
Fibrous structure, 221
File,

Lamp-stand, 23

20

Lanthanum, 65
Lead, 87 Lead, granulated, 26
Leus, 20

Filtering, 22 Filter-paper, 21 Flame coloration, 35 table of, 136

,

Flame, nature

of, 31

Fluorine, 75 Foliated structure, 221 Forceps, 15 Fracture, 225 Fuel, 13 Funnel, 21

Fusibility, scale of, 230

Lithium, 90 Litmus-paper, 25 Loops, 16 Luster, 227

Macro-dome, 201, 215 Macro-piuacoid, 201, 215

Magnesium,

91

Magnesium
Mammillnry

ribbon, 26

Fusion, 33

Magnet, 20 Malleable, 226

structure, 222

Gadolinium, 65 Gallium, 78 Germanium, 78

Glass tubing, 17 Globular structure, 222 Glowing, 231 Glucinum (see Beryllium). 53 Gold, 78 Goniometers, 158 Granular structure, 221 Greasy luster, 228 Gypsum tablets, 17

Manganese, 92 Massive structure, 221 Mathematical ratio, law Mercury, 93

Metallic luster, 227 Metal scoop, 21

of, 160

Micaceous structure, 221 Mineral kingdom, 1

Minerals,
,

Habit of crystals, 165 Hackly fracture, 225

Hammer,
Heavy

20 Hardness, scale

of,

226

solutions, 236, 238

determination of, 239 tables for determination, 245 Molecular weight, 5 Molecules, 3 Molybdenum, 95 Monoclinic system, 208 Mortars, 19 Mouthpiece, 12
,

Helium, 80

Hemihedrism, 164

Neodymium, 65
Nickel, 96

Hemimorphism, 164
Hexagonal-hombohedral system, 191

Niobium, 98

INDEX TO SUBJECT-MATTER.
Nitric acid, 28 Nitrogen, 99

305
crystals,

Pseudomorphous
, ,

218

Pyramids, hexagonal, 186

mouocliuic, 209 orthorhombic, 200
tetragonal, 177

Nitrohydrochloric acid, 28 Non-metallic luster, 228 Normal forms, 164

Octahedron, 170
Oil for fuel, 14 Oil of vitriol, 28

tricliuic, 215 Pyritohedrou, 173 Pyroelectricity, 231

,

Oily luster, 228

Open
,

tubes, 18 table of reactions, 140

Organic matter, 61 Ortho-dome, 210 Ortho-pitiacoid, 210

Radiated structure, 222 Rare-earth metals, 65 Reagents, 24

,

reactions with, 151

Ortuorhombic system, 199

Reamer, 11 Reducing flame, 36

Reduction, 36

Osmium. 104
Oxidation, 35 with nitric acid, 120 Oxide of copper, 26 Oxidizing flame, 36 Oxygen, 100
,

Reniform structure, 222 Resinous luster, 228

Rhodium, 104 Rhombohedral system, 191

Rhoinbohedrons, 191
Roasting, 39 Rocks, 2 Rubidium. 106 Ruthenium, 104
Salts, 4

Palladium, 104 Parameters, 160 Parting, 224 Pearly luster, 228 Pentagonal dodecahedron, 173 Phosphorescence, 231 Phosphorus, phosphoric acid, 101 Phosphorus salt, 25 , table of reactions, 149 Pinacoids, hexagonal, 187 monocliuic, 210 orthorhombic, 20J tetragonal, 179 , triclinic, 215 Pipette, 23 Platinum, 103 Platinum chloride, 28
, ,
!

Samarium, 65
Scale of hardness, 158 Scalenohedron, hexagonal, 192 tetragonal, 184 Scandium, 65 Scoop, 21 Selenium. 107 Separatory funnel, 238 Silicon, 107
,

loops, 16

pointed forceps, 15 spoon, 16 wire, 16 Pliers, 20 Porcelain crucibles, 22 dishes, 22 Potassium, 105
bisulphate, 25

Silky luster, 228 Silver, 113 Silver nitrate, 30 Sodium, 115 Sodium carbonate, 24

metaphosphate, 25
,

table of reactions, 149

phosphate, 30 tetraborate, 24
Spatula, 21 Specific gravity, 232

bisulphate and fluorite, 26 ferricyaulde, 30 ferrocyanide, 30 hydroxide, 28 iodide and sulphur, 26 mercuric iodide solution, 236 nitrate. 26

pyrosulphate, 25

Praseodymium, 05
Precipitation, 30

Prisms, hexagonal, 187 mouoclinic, 209

,

orthorhombic, 200 tetragonal, 179 triclinic, 215

Sphenoid, orthorhombic, 208 tetragonal, 183 Splintery fracture, 225 Spring Balance, 234 Stalactitic structure, 222 Streak, streak plates, 228 Strontium, 116 Structure of minerals, 221 Sub-metallic luster, 227 Sulphates, 122 Sulphides, 118 Sulphur, 118 Sulphuric acid, 28 Symbols, 3 Symmetry, 162
,

Systems of

crystallization, 169, 219

306
Tantalum, 123 Tellurium, 124 Tenacity, 226 Terbium, 65 Test-paper, 25
Test-tube, 21 Test-tube holder, 21 Test-tube stand, 21

INDEX TO SUBJECT-MATTER.
Twin
Turmeric-paper, 25
crystals, 167

Uneven fracture, 225 Uranium, 129

Valence, 4

'

Tetragonal system, 177 Tetrahedron, 175 Tetrahexahedron, 172 Thallium, 125 Thorium, 65 Thulium, 65 Tin, 125 granulated, 26 Titanium, 127 Trapezohedron, hexagonal, 197
,

Vanadium, 130
Vitreous luster, 228
Watch-glasses, 21 Water, reagent, 27
,

test for, 81

Water

of crystallization, 81

Wash-bottle, 23 Washing. 22 Westphal Balance, 236

isometric, 171 Triclinic system, 214

,

Trisoctahedron, 172 Tristetrahedron, 175 Trimorphism, 8 Truncations, 167 Tungsten, 128

Ytterbium, 65 Yttrium, 65
Zinc, 130 granulated, 26
,

Zirconium, 133

INDEX TO MINERALS.
Aanerodite, 254 Acanthite, 251 Achroite, 300 Acraite, 270 Actinolite, 288
Anglesite, 260 Aubydrite, 274 Ankerite, 289 Annabergite, 267 Auortbite, 280, 285 Anortboclase, 285 Antbopbyllite, 287, 301 Antimony, 249 Antimony Glance, 249 Apatite, 276, 293 Apbtbitalite, 272 Apjobuite, 291 Apopbyllite, 282 Aquamarine, 287, 300 Aragonite, 289 Ardennite, 286 Arfvedsouite, 270 Argentite, 251 Argyrodite, 253 Arsenic, 246 Arseuiosiderite, 267 Arsenolite, 258 Arseuopyrite, 247
Barysilite, 262

Barytocalcite, 289 Bastnasite, 297 Bauxite, 297

Bayldonite, 260
Bechilite, 277

Adamite, 275
Adelite, 275
^Egirite, 270

Beegerite, 251 Belonesite, 277

^Enigmatite, 270 JSscbyuite, 300 Agalraatolite, 296 Agate, 299 Agricolite, 262 Aguilarite, 248 Aikinite, 251 Alabandite, 253 Alabaster, 274 Albite, 285 Alexandrite, 301 Algodonite, 246 Allactite, 275, 292
Allanite, 254, 269, 280

Bementite, 281 Berauuite, 268 Bertbierite, 250 Bertrandite, 301 Beryl, 287, 300 Beryllonite, 27?
Berzelianite, 24.7 Berzeliite, 275

Beudantite, 260
Bieberite, 291

Bindbeimite, 261 Binnite, 246

Biotite, 269, 270,

284

Bismutb, 253

Allemontite, 246 Alloolasite, 246

Allophaue, 294 Almandite, 270 Altaite, 248

Asbestus, autbopbyllite,287, 301 serpentine, 281, 295

,

Alumian, 291 Ahnninite, 291 Aluminium Ore, 297 Alunite, 290, 296 Aluuogen, 291
Alurgite, 284

tremolite, 288 Asbolite, 292 Astropbyllite, 269

,

Amalgam, 253 Amarantite, 267 Amblygonite, 283 Amesite, 296 Amethyst, !<J99

Ammonia Alum,
Amphibole, 288
Analcite, 282 Anatase, 299 Audalusite, 301 Andesite, 285 Andorite, 249 Andradite, 269

291

Atacamite, 263 Atelestite, 262 Atopite, 298 Augelite, 293, 296 Augite, 288 Auricbalcite, 290 Automolite, 298 Autuuite, 276 Awaruite, 255 Axinite, 285 Azurite, 263
Babingtonite, 270, 288 Baddeleyite, 302 Barite, 274 Barium Feldspar, 285 Barrandite, 268

Bismutb Glance, 251 Bismuthinite, 251 Bismutite, 262 Bismutosmaltite, 246 Bismutosphaerite, 262 Bixbyite, 253 Black Jack, 252 Black Lead, 256 Blende, Zinc Blende, Blodite, 272 Blue Vitriol, 264 Bobierrite, 277 Bog Iron Ore, 292 Bog Manganese, 292 Boleite, 261 Boracic Acid, 277 Boracite, 277 Borax, 273, 277 Borickite, 268 Bornite, 252 Botryogeu, 266 Boulangerite, 249 Bournonite, 249 Boussingaultite, 272
307

308
Brackelmschite, 260 Brandtite, 275 Bnmuite, 254, 256 Breithauptite, 250 Breunuerite, 289, 290 Brewsterite, 282 Brochantite, 264 Broinlite, 289 Bromyrite, 259 Brongniardite, 249 Bronzite. 287,301 Brookite, 300 Brown Hematite, 266, 292 Brucite, 290, 293 Brushite, 276 Bunsenite, 292
Cabrerite, 267 Cacoxeuite, 268 Calamine, 278, 294. Calaverite, 248 Calcioferrite, 268 Calciovolborthite, 265 Calcite, 289 Caledonite, 260 Callaiuite, 293 Calomel, 258 Cancriuite, 278 Canfieldite, 253 Cappelenite, 279 Caracolite, 260 Carbonado, 298 Carminite, 260 Carnallite, 271 Carnelian, 302 Carpbolite, 286 Carphosiderite, 267 Carrol lite 252 Caryinite, 260 Caryoceriie, 295 Cassiteiite, 299 Castanite, 267 Catapleiite, 281 Celestite, 274 Cenosite, 278 Cera rgy rite, 259 Cerite/294 Cemssite, 259 Cervantite, 297 Cbabazite, 282 Chalcanthite, 264 Chalcedony, 302 Chalcocite, 252 Chalcodite, 269 Chalcomenite. 265 Chalcopbanite, 256 Cbalcophyllite, 265 Chalcopyrite, 252 Chalcosiderite, 265, 268 Chalcostibite, 250 Chenevixite, 264 Chert, 299 Chiastolite, 301 Childrenite, 268

INDEX TO MINERALS.
Chiolite, 274 Chiviatite, 251

Cuprite. 254, 263 Cuprobismutite, 251

Chloanthite, 247
Chlorite, 284, 296 Chloritoid, 301

Chloropal, 295 Choudrodite, 294 Chrome Clinochlore, 296 Garnet, 299 Mica, 284 Chromic Iron, 256 Chromite, 256, 298 Chrysoberyl, 301 Chrysocolla, 295 Chrysolite, 294 Chrysoprase, 302 Chrysotile, 281, 295 Churchite, 293 Cimolite, 297 Cinnabar, 258 Cirrolite, 276. 283 Claudeiite, 258 Clausthalite, 248 Clinochlore, 284, 296 Clinobediite, 278 Clinocksite, 264 CHnohumite, 294 Clinozoisite. 287 Clintonite, 296 Cobalt Bloom, 267 Cobaltite, 246 Colemanite, 277 Collophanite, 276 Collyrite, 297 Coloradoite, 248 Columbite, 254. 257 Comptonite, 278 Conichalcite. 264 Connellite, 263 Cookeite, 284 Copiapite, 267 Copper, 253 Glance, 252 Nickel, 247 Pyrites, 252 Copperas, 266 Coquimbite, 266 Cordierite, 287, 300 Cornwallite, 265 Corundophilite, 296 Corundum, 299 Corynite, 247 Cosalite, 251 Cotu unite, 258, 261 Covellite, 252 Crednerite, 256 Crocidolite, 270 Crocoite, 261 Cronstedtite, 269 Crookesite, 247 Cryolite, 274 Cubanite, 252 Cuinengite, 261

284,

Cuprodescloizite, 26? Cuproiodargyrite, 25 Cuprotungstite, 265 Cyanite, 302 Cyanochroite, 264' Cyanotrichite, 264 Cylindrite, 249 Cyprusite, 267
Dahliite, 290 Daualite, 269, 294

Danburite, 285 Darapskite, 272 Datolite. 278 Daubreelite, 262 Daubreeite, 255 Dawsonite, 273, 289 Derbylite, 255
Descloizite, .260

Desmine, 282
Deweylite, 281, 295 Diadochite, 266 Diallogite, 290 Diamond, 298 Diaphorite, 249 Diaspore, 301 Dicldnsouite, 276 Dietrichite, 291 Dietzeite, 274 Dihydrite, 265 Diopside, 288 Dioptase, 294 Disluite, 298 Disthene, 302 Dolerophanite, 264 Dolomite, 289 Domeykite, 246 Dry-bone Ore, 290 Dufrenite, 268 Dufrenoysite, 246 Dumortierite, 301 Durangite, 275 Durdenite, 268 Dysanalyte, 257 Dyscrasite, 250

Ecdemite, 260
Elseolite,

Edingtonite. 278 280 Electrum, 253 Eleonorite, 268 Embolite, 259 Emerald, 287, 300 Emerald Nickel, 290 Emery, 299 Emplectite. 251 Enargite, 246 Endlichite, 260 Enstatite, 287, 301 Eosphorite, 276

Epiboulangerite, 249

INDEX TO MINERALS.
Epididymite, 287 Epidote, 287 Epigenite, 246 Epistilbite, 282
Gearksutite, 274 Gehlenite, 280, 294
Geikielite, 257
Salt,

309
Hisingerite, 295 Hceruesite, 275

Epsomite,

Epsom

272

Erinite, 265

Erythrite, 267 Ettringite, 274 Eucairite, 247

Genthite, 295, 297 Geocronite, 249 Gerlmrdtite, 264 Gersdorffite, 247 Gibbsite. 293, 297

Homilite, 279 Hopeite, 277

Horn

Euchroite, 265 Euclase, 288, 301 Eucolite, 279 Eudialyte, 279 End idy mite, 288 Eulyti'te, 262 Euxenite, 300 Evansite, 293
Fairfieldite, 276

Gismondite, 278 Glauberite, 274 Glauber Salt, 272 Glaucodot, 246 Glaucophane, 288 Glockerite, 267 Gmeleuite, 282 Goethite, 266, 292 Gold. 253
Goslarite, 291 Gothite, 266, 292

Silver, 259 Hornblende, 288 Hortonolite, 269 How lite, 285 Htibnerite, 283 Huebnerile, 285 Humite, 294 Hureaulite, 276 Hyacinth, 299 Hyalite, 302 Hyalophane, 285 Hyalotekite, 262

Hydrargillite, 297

Falkeubaynite, 250 Famatiuite, 250 Faujasite, 282 Fayalite, 269 Feather Ore, 249 Feldspar, 285 Fels5banyite, 291 Fergusonite, 299 Ferronatrite, 266 Fibroferrite, 267 Fibrolite, 301 Fillowite, 276 Fisoherite, 293 Flinkite, 275 Flint, 299 Fluellite, 297 Fluocerite, 293 Fluorite, 274 Fluor Spar, 274 Footeite, 263 Forbesite, 267 Forsterite, 294 Fowlerite, 286 Franckeite, 249 Fraukliuite, 255 Freibergite, 250 Freieslebenite, 249 Friedelite, 281 Fuehsite, 284
Gadolinlte, 280, 294

Goyazite, 296 Graphite, 256

Hydroboracite, 277 Hydrocerussite, 259 Hydrocynnite, 264 Hydrogioberite, 289

Gray Copper, 250 Greenockite, 292 Grossularite, 287 Grunlingite, 248 Guanajuatite, 248 Guarinite, 286 Guitermanite, 246 Gummite, 293 Gymnite, 281, 295 Gypsum, 274 Gyrolite, 278
Haidingerite, 275 Halite, 271 Halloysite, 297 Halotrichite, 266 Hambergite, 300

Hydro- hematite,

255, 292 Hydro-herderite, 276, 283 Hydromagnesile, 239 Hydronepbelite, 278 Hydrophilite, 271 Hydrotalcite, 293 Hydroziucite, 290 Hypersthene, 270, 301

Idocrase, 287
Ihleite, 266
Ilesite, 291 Ilmenite, 255, 257 Ilvaite, 254, 269 Inesite. 281

Hamlinite,283 Hauksile, 271

Harmotome, 282, 286 Hatchettolite, 298

Hauchecornite, 250 Hnuerite, 253 Hausrnannite, 256 Hautefeuillite, 277 Haiiyne, 279 Haiiynite, 279 Heavy Spar, 274 Hedenbergite, 288 Heintzite, 277 Helvite, 279 Hemafibrite. 275 Hematite, 255, 292 Hematolite, 292 Hemimorphite, 294 Hercynite, 298 Herderite, 276, 283 Herrengrundite, 264 Hessite7 248 Heulaudite, 282 Hiddenite, 285 Hielrnite, 257 Hiortdahlite, 280

Indicolite, 300 lodobromite, 259 lodyrite, 259 lolite, 287, 300 Indium, 257 Iiidosmine, 257 Iron, 255 Iron Chrysolite, 269 Iron Pyrites, 252 Isoclasite, 276

Jacobsite, 255

Jade, 288
Jadeite, 288

Gahnite, 298 Galena, 251 Galenobismutite, 251 Ganomalite, 262 Ganophyllite, 278 Garnet, 287 Almandite, 270 Andradite, 269 Grossularite, 287 Pyrope, 287 Spessartite, 286 Uv;irovito, 299 Garnierile, 295, 297 Gay-Lussite, 273

Jamesonite, 249
Jarosite, 266

Jasper, 299
Jefferisite, 281

Jeffersonite, 286

Jeremejevite, 300 Johannite, 291 Jordanite, 246

Kainite. 271 Kainosite, 278

KaiseriU

272

Kalinite, 272, 290, 291 Kallaite, 302

310
Kallilite, 250

INDEX TO MINERALS.

INDEX TO MINERALS.
Parisite, 290

311
Scheelite, 283, 298 Schefferite, 286

Pyrite, 252

Partschinite, 286 Peacock Ore, 252 Pearceite, 246 Pearl Spar, 289 Pectolite, 282

Peganite, 293
Penfieldite, 261 Penniuite, 284, 296

Pentlandite, 252 Percylite, 261 Periclase, 293 Peridot, 294 Perovskite, 257, 297
Petalite, 285 Petzite, 248

Pyroaurite, 292 Pyrochlore, 298 Pyrochroite, 292 Pyrolusite, 256 Pyromorphile, 260 Pyrope, 287 Pyrophanite, 256 Pyrophyllite, 296 Pyrosmulite, ~69 Pyrostilpuite, 259 Pyroxene, 288 Pyrrhotite, 252

Schirmerite, 251

Quartz, 299 Quenstedtite, 266

Phacolite, 282

Pharmacolite, 275 Pharmacosiderite, 267 Phenucite, 300 Phillipsite, 282 Phlogopite, 284 Phoeuicochroite, 261 Phosgenite, 259 Phosphosiderite, 268 Phospburanylite, 276 Picroinerite, 272 Piedin6ntite, 286 Pinakiolite, 277 Pinnoite, 277 Pirssonite, 273 Pisanite, 264 Pitch Blende, 257 Pitticite, 267 Plagionite, 249 Platinum, 257 Plattnerite, 254, 262 Plumbogummite, 260 Polianite, 256 Pol Incite, 295 Polyargyrite, 250 Polybnsite, 250 Polycrase, 300 Polydyniite, 252 Polyluilite, 274 Polymignite, 257 Porcelain Clay, 297 Potash Alum, 272, 290, 291 Potash Mica, 284 Potash Feldspar, 285 Powellite, 277 Prehuite, 288, 287 Prismatine, 301 Prochlorite, 296 Prolectite, 294 Prosopite, 290, 297 Prousiiie, 259 Pseudobrookite, 255, 257 Pseudomalachite, 265 Psilomelane, 256 Psittadnite, 260 Ptilolite. 286 Pucherite, 202 Pyrargyrite, 250, 259

Raimondite, 267 Ralstonite, 297 Rammelsbergite, 247

Raspite, 261 Realgar, 258 Reddingite, 276 Red Ziuc Ore, 292 Reiuite, 254

Remingtonite, 290 Rezybanyite, 251 Rhabdophanite, 293 Rhagite. 262 Rhodizite, 277 Rhodochrosite, 290 Rhodonite, 286 Richterits, 286 Riebeckite, 270 Riii kite, 280 Ripidolite, 284, 296 Rock Crystal, 299 Roeblingite, 262 Rospperite, 269 Romeite, 263 Romerite, 266 Roscoelite, 284 Roseliie, 275 Rubellite. 300 Ruby, 299 Copper, 263 Silver, 259 Spinel, 298 Rutile, 299
Safflorite,

246

Sal-ammoniac, 258
Sal-soda. 271
Suit,

Common,

271

Salt of Phosphorus, 277

Samarskite, 254 Sanidine, 285

Sapphire, 299 Sapphinne, 301 Sarcolite, 280 Sartorite, 246 Sassolite, 277 Scapolite, 283, 287 Schapbachite, 251

Schorlomite, 280 Schrottcrite, 297 Schwartzenbergite, 261 Schwatzite, 250 Scolecite, 278 Scored ite, 267 Scovillite, 293 Selen-tellurium, 247 Sellaite, 283 Semseyite, 249 Senarmontite, 258 Sepiolite, 281, 295 Serpentine, 281, 295 Seybertite, 296 Siderite, 266, 290 Sideronatrite, 266 Sillimauite, 301 Silver, 253 Silver Tetrahedrite, 250 Sipylite, 299 Skutterudite, 246 Smaltite, 246 Smithsonite, 290 Soapstone, 284, 296 Soda Feldspar, 285 Soda Mica, 284 Soda Niter, 273 Sodalite, 279 Spadaite, 278 Spangolite, 263 Spathic Iron, 266, 290 Specular Iron, 255 Sperrylite, 247 Spessartite, 286 Sphserite, 293 Sphserocobaltite, 290 Sphalerite, 252, 292 Sphene, 283, 286 Soinel, 298 Spodumene, 285 Stannite, 252 Staurolite, 300 Steatite, 296 Siephanite, 250 Stercorite, 277 Sternbergite, 252 Stibiconite, 297 Stibiotautalite, 297 Stibnite, 249 Stilbite, 282 Stilpnomelane, 269 Stolzite, 261 Strengite, 268 Stromeyerite, 252 Stroutianite, 289 Struvite, 277 Stylotypite, 250 Sulphohalite, 271 Sulphur, 258 Sussexite, 277 Svabite, 275

312
Svanbergite, 296 Sychuodyinite, 252 Sylvauite, 24b Sylvite, 271

INDEX TO MINERALS.
Triphylite. 268
Tripiite, 268

Wagnerite, 277 Waipurgite, 262

Tiiploidite, 268

Warren ite, 249

Warwickite, 257, 297 Wattevillite, 274

Symplesite,

22

Synadelpliite, 75 Syngenite, 272, 274 Szaibelyite, 277 Szinikite, 291

Tachydrite, 271 Tagilite, 265 Talc, 284, 296

Tantalite, 257

Tripuhyite, 263, 297 T r5ge rite, 275 Troilite, 252 Troim, 271 Troostite, 279 Tscheffkinite, 280 Tschermigite, 291 Tungstite, 298
Turfite. 255, 292 Turingite, 269 Turquois, 302
Tyrolite, 264

Wavel lite, 296

Wellsite. 282 Wernerite, 283, 287

Whewellite, 290

White Iron

Pyrites, 253

Whitueyite, 246 Willemite, 294

Witherite, 273 Wittichenite, 251 Wohlerite, 280 Wolfuchite, 247

Tupalpite, 248 Tapiolite, 257 Tavistockite, 296 Taylorite, 272 Tellurium, 248 Teunantite, 246 Tenorite, 254 Tephroite, 279 Tetradymite, 248 Tetrahedrite, 250

Tysonite, 297
Ulexite, 277

Wolframite, 254, 270

Ullmannite, 250 Umangite, 247 Uraninite, 257 TJran Mica, 265 Uranocircite, 276 Uranophane, 294 Uranopiljte., 291 Uranospinite, 275 Uranothallite, 289 Utahite, 267 Uvarovite, 299
Valentinite, 258

Wolfsbergite, 250 Wollastouite, 283 Wulfenite, 261 Wurtziie, 292

Xanthoconite, 259 Xauthophyllite, 296

Xanthosid'erite, 266, 292

Thaumasite, 273, 289 Theiiardite, 272 Thermonatrite, 271 Thornsenolite, 274 Thomson ite, 278 Thorite, 294 Thuringite, 269 Tiemannite, 247 Tilasite, 275 Tin, 253 Tin Pyrites, 252 Tin Stone, 299 Titanic Iron, 255 Titanite, 283, 286 Topaz, 300 Torbernite, 265 Tourmaline, 285, 300 Tremolite, 288 Trichalcite, 265 Tridymite, 299 Trimerite, 283

Xenotime, 296
Yttrocerite, 293
Zaratite, 290

Vauadinite, 260 Variegated Copper, 252 Variscite, 296 Vauquelinite, 260 Vertniculite, 281 Vesuviauite, 287 Veszelyite, 264 Vivianite, 268 Volborthite, 265 Voltaite, 266 Voltzite, 293

Zepharovicbite, 293 Zeunerite, 264 Zioc, 253 Zinc Blende, 252, 293 Zinc Spinel, 298 Zincaluminite, 291 Zincite, 292 Zi uken ite, 249 Zinnwaldite, 270, 284 Zircon, 299 Zirkelite, 297 Zoisite, 287
Zorgite, 247

Wad, 293

Zunyite, 299

u.

Uar*

RETURN
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