Gold in Minerals and the

Composition of Native Gold

Gold in Minerals and the
Composition of Native Gold

By Robert S. Jones and Michael Fleischer

GEOLOGICAL SURVEY CIRCULAR 612

Washington 1969
 United States Department of the Interior
WAl.TfR J. HICKEL, Secretary

Geological Survey
William T. Pecora, Director

Free on application to the U.S. Geological Survey, Washington, D.C. 20242

 CONTENTS

Page
Abstract -----------------------------------------------~----------------- 1
Introduction -------------------------------------------------------------- 1
General geochenrlcal considerations ----------------------------------------- 1
Gold in minerals ------------------------------------------------------ _ 2
Composition and the fineness of gold ---------------------------- ___ 13
References cited --------·------- _____________________ ______________ ____ _ 15

TABLES

Page
'fABLE 1. Major gold-bearing minerals ----------------------------------- __ 2
2. Analyses of precious metals in minerals made before 1955 _______ _ . _ 3
3. Analyses of gold in minerals made since 1954 --------------------- 10
4. Variation in fineness of gold with depth, Lily mine, Transvaal, South
Jlfrica -------------------------------------------------------- 14
5. Fineness of mill bullion prior to 1882 at the Homestake nrlne, South
Dakota -------------------------------------------------------- 15

Ill
 GOLD IN MINERALS AND THE COMPOSITION OF NATIVE GOLD

By ROBERT S. JONES and MICHAEL FLEISCHER

ABSTRACT much lower concentrations in the sulfiie phase,

Gold occurs in nature mainly as the metal and as
and occurs in much lesser amount~ in the
various alloys. It forms complete series of solid solu- silicate phase. Gold occurs in natur~ mainly
tions with silver, copper, nickel, palladium, and as the metal and as various alloys, especially
platinum. In association with the platinum metals, gold with silver, and as intermetallic co:'llpounds.
occurs as free gold as well as in solid solution. Laboratory studies show that gold can form
The native elements contain the most gold, followed
by the sulfide minerals. Several gold tellurides are complete series of solid solutions with silver,
known, but no gold selenides have been reported, and copper, nickel, platinum, and palla:dium. Gold
only one sulfide, the telluride-sulfide mineral nagyagite, is commonly present in association with plati-
ii:; known. num metals; most microscopic stuc"ies have
The nonmetallic minerals carry the least gold, and shown that free gold is present in platinum,
the light-colored minerals generally contain less gold
than the dark minerals. but a recent electron-probe analysis of ferro-
Some conclusions in the literature are conflicting in platinum shows uniform distributioi' of gold
regard to the relation of fineness of native gold to its ( Ottemann and Augustithis, 1967). This distri-
position laterally and vertically within a lode, the bution indicates that gold and platinum aTe
nature of the country rocks, and the location and size
of nuggets in a streambed, as well as to the variation
present in solid solution.
of fineness within an individual nugget. Several gold tellurides are known (table 1),
but no gold selenides have been repC'...-ted, and
INTRODUCTION the only minera~ in which gold is certainly
combined with sulfur is the telluride-sulfide,
This report on the occurrence of gold in
nagyagite. Gold commonly occurs in sulfide
minerals and on the fineness of native gold
minerals, but largely, if not entirely, as the
was prepared as background material for the
free metal; it is uncertain whether any gold
Heavy Metals program of the U.S. Geological
occurs in these minerals in true isomorphous
Survey, an intensified program of research
substitution.
on new sources of heavy metals, including
gold. It is even less likely that gold is present
in ionic substitution in silicate miner·als. Man-
GENERAL GEOCHEMICAL CONSIDERATIONS tei and Brownlow (1967) state, "Tl'e concen-
tration of gold in the various minerals is proba-
Gold belongs to group Ib of the periodi.c bly due to an inclusion or entrappinr-- phenom-
table, as do silver and copper. Its atomic num- ena rather than to ionic substitutior. Because
ber is 79, and atomic weight is 197.0; it con- of its oxidation potenti.al, it would 1~<~ difficult
sists of a single isotope. Its metallic radius for gold to become oxidized and thus be able
is 1.44A., univalent ionic radius 1.37A., and to take part tn ionic substitution. Krauskopf
trivalent ionic radius 0.85A. (1951) states that simple ionic goli can not
Gold is strongly siderophilic and somewhat exist in geological environments, alth('mgh com-
chalcophilic; that is, it tends to be co,ncen- plex ions containing gold may form. Ringwood
trated in the metallic phase of meteorites, with (1955) points out that Au+, because of its

1
large electronegativity, would form a very been made by more sensitive methods, mostly
weak covalent bond, and one which would pre- by neutron activation, than the older ones,
fer not to form. Thus the gold of a crystallizing and values as low as 0.0003 ppi1. (part per
magma tends to concentrate in the residual million) are reported. However, comparatively
fluids. The factors which would control the few neutron activation analyses . of rock-form-
amount of gold entrapped in a given mineral ing minerals have been reportei in recent
would be the concentration of gold in the years. The older analyses tend to be significant-
magma at the time of crystallization and the ly higher than more recent analyses of the
type of crystal structure formed by the min- same minerals. The highest gold values listed
eral." in tables 2 and 3 are reported for the native
Helgeson and Garrels (1968), on the basis elements; next highest are for the sulfide min-
of thermodynamic calculations, think that all erals.
but marginal or low-grade hydrothermal native TABLE 1.-Major gold-bearing minerals
gold deposits form above 175°C and, at ele-
Gold Au. Cubic, sp gr 19.3 (pure Au),
vated temperatures, most hydrothermal solu- decreasing with ircreasing con-
tions are probably distinctly acid. They believe tent of Ag. Form!;; a complete
that gold is present primarily in the form series of solid solutions with silver
of aurous chloride complexes in contrast to (see electrum and silver, below);
the low-temperature considerations of Kraus- commonly contains 10-15 percent
Ag. Also reported in percent: Cu
kopf (1951) and Cloke and Kelly (1964) who (ma..."X: 20.4), Fe (ma.x 0.1), rarely
suggest that the aqueous species AuC17 is Bi (max 2.9), Sn (max 0.3), Ph
the principal form of dissolved gold in hydro- (ma..."X: 0.2), Zn (max 0.8), AI (max
thermal solutions. 0.10), Mn (max 0.002). See sec-
tion "Composition and Fineness
Goni, Guiiiemin, and Sarcia (1967) have
of Gold."
investigated the stability of colloidal suspen-
Varieties:
sions of gold and the formation of nuggets. Electrum, (Au,Ag), argentian geld with >20
Stable colloidal suspensions of ionic and even percent Ag.
metaiiic gold can form which can be floccu- Porpezite, (Au,Pd), palladian go1d with 5-10
lated to form nuggets. Textures common in percent Pd.
Rhsxlite, (Au,Rh), rhodian gold(?) with 34-43
gold deposits can be reproduced in gold films
percent Rh.
formed by the diffusion of gold solutions Auricupride (cuproauride) has generally been
through silica gel. considered to be a solid solution of gold in
Gold occurs in notable amounts in hydro- copper, near AuCua in. composWon. Ramdohr
thermal veins and in placer deposits, and to (1967) states, however, that study of "red
gold" from Laksia, Cyprus, has shown the
a much lesser extent in pegmatites and con- presence of three· distinct phases Au-Cu solid
tact metamorphic deposits. Commo.n minerals solutions, the compound AuCua with a
_associated with gold in veins are quartz and characteristic violet color, and the compound
pyrite. Some other common minerals associ- Au Cu.
ated with gold (Lincoln, 1911; Schwartz, 1944) Aurosmirid, aurosmiridium ( =aurian osmiri-
dium) Au 19.3 percent. ProbabJy a mixture
are pyrrhotite, arsenopyrite, chalcopyrite, sphal- containing gold.
erite, galena, molybdenite, tellurides, selenides, (Palache and others, 1944, p. 111).
magnetite, scheelite, feldspar, sericite, biotite,
Silver (Ag,Au). Aurian silver, with 0-50
chlorite, amphiboles, garnet, tourmaline, car- percent Au.
bonates, and fluorite. Kiistelite=aurian silver.
Gold-amalgam A112Hga(?)
GOLD IN MINERALS Au 34.2-41.6 percent.
Maldonite Au2Bi. Cubic.
Minerals that have been reported to contain Au 64.5-65.1 percert; Bi 34.9-
major amounts of gold are listed on table 35.5 percent.
1. Many analyses have been made for some Aurostibite AuS~. Cubic, pyrite tYf<:'\.

of the precious metals in minerals that con- Au 43.5-50.9 percent.

Krennerite AuTe2. Orthorhombic.
tain little gold;: those made before 1955 are Au 30.7-43.9 percent.
listed in table 2 and those made since 1954 M iillerine = Krennerite
are in table 3. The more recent analyses have Speculite = Krennerite (?)

2
 TABLE l._JMajor gold-bearing minerals-Continued TABLE 1.-Major gold--bearing m.inerals-Concluded
Calaverite AuTe2. Monoclinic. Hessite Ag2Te. Monoclinic, pseudocubic.
Au 39.2-42.8 percent. Reported to contain as much as
Coolgardite =a mixture of calaverite, coloradoite, 4.7 percent Au.
and sylvanite. Montbrayite Au2Tea. Triclinic.
Sylvanite (Au,Ag) Te2, with Au :Ag usually Au 38.6-44.3 percent.
nearly 1:1, that is, AgAuTe4. Nagyagite PbsAu(Te,Sb)4Ss-s( ?) •
Monoclinic. Monoclinic ( ?) .
Au 24.25-29.9 percent. Au 7.4-10.2 percent.
Goldschmidtite= Sylvanite. Silberphyllinglanz = N agyagite.
Kostovite CuAuTe4 Blatterine = N agyagite.
Au 25.2 percent (Terziev, 1966). Aurobismuthinite (Bi, Au,Ag) sSs ( ?)
Petzite AgaAuT~ Au 12.3 percent; Ag 2.3 percent.
Au 19.0-25.2' percent. Probably a mixture (Palache and
Antamokite=a mixture of petzite and altaite. others, 1944 p. 278).

TABLE 2.-Analyses of precious metals in minerals made before 1955

[Minerals containing higher amounts of gold are listed in table l. N. D., not determined]

Gold Silver Platinum

Mineral and locality (ppm) (ppm) (ppm) Remarks Reference

Elements

Arsenic, As
Germany, Andreasberg, Harz ___ _ 150 >1,000 20 One sample __ Noddack and
No·ldack (1931).
Copper, Cu
Norway, Kviteseid --------------- 200 >1,000 .3 Two samples _ Do.
Iridosmine, ( Os,Ir)
Australia, New South Wales _____ 800 >1,000 Eight samples Do.
U.S.S.R., Urals ----------------- >1,000 600 >1,000 Do.
Iron, (Fe,Ni)
Greenland, Ovifak, Disko _______ _ 1-5 5-10 5 In basalt ____ Goldschmidt and
Pe...,ers (1932).
United States:
Cal).yon Diablo, Ariz _________ _ 5 5 10-100 In meteorite _ Do.
Holbrook, Ariz ---------------- 10 1 10-100 _____ do ____ _ Do.
Mexico
Coahuila ------------~--------- 1-5 5 10-100 _____ do ----- Do.
Chile, Corrizatillo --------------- 5-10 5-10 10 In meteorite _ Do.
Germany, Biihl, near Kassel _____ _ .5 5-10 .2 In basalt ___ _ Do.
Czechoslovakia, Knyahinya ______ _ 10 1 10-100 In meteorite _ Do.
Portugal, Sao Juliao de Moreira __ 10 5 10-100 _____ do ____ _ Do.
Platinum, Pt
Brazil -------------------------- > 1,000 >1,000 >1,000 One sample __ Noddack and
Ncddack (1931).
U.S.S.R., Urals ------------------ 500 200 >1,000 Eleven sam- Do.
ples.
Platiniridium, (Ir,Pt)
Brazil -------------------------- 200 >1,000 One sample __ Do.
Schreibersite, (Fe,Ni) aP
Portugal, Sao J uliao de Moreira __ 1 10 1.2 In meteorite. Gold ""<'hmidt and
Two samples. Peters (1932).

Sulfides, arsenides, selenides, and tellurides

Domeykite, CuaAs
Mexico, Paracatas 25 >1,000 5 One sample __ Noddack and
Noddack (1931).
Argentite, AgsS
Germany, Freiberg 200 >1,000 4 Two samples _ Do.

3
 TABLE 2.-Analyses of precious metals in minerals made "efore 1955-ContinU6d

Gold Silver Platinum

Mineral and locality (ppm) (ppm) (ppm) Remarks lkoference

Sulfides, arsenides, selenides, and telluride.-Gontinued

Berzelianite, C111Se
Sweden, Skrikerum 100 >1,000 10 One sample __ Noddack and
Nod<lack (1931).
Chalcocite, CusS
United States, Butte, Mont ------- 12 500 .1 Six samples _ Do.
Bornite, CusFeS,
Germany, Mansfeld -------------- 8 >1,000 .2 Four samples_ Do.
Galena, PbS
South Africa -------------------- 30 >1,000 .8 Five samples _ Do.
Clausthalite, PbSe
Germany, Tilkerode, Harz _______ _ 250 >1,000 40 One sample __ Do.
Altaite, PbTe
U.S.S.R., Altai ------------------ 400 >1,000 10 ~---- do ----- Do.
Alabandite, MnS
Roumania, Nagyag, Siebenbiirgen__ 30 .02 _____ do _____ Do.
2
Sphalerite, (Zn,Fe) S
Germany:
Silesia _______________________ _ 3 150 0 Three samples Do.
Biihl, near Kassel ------------- .5 5 In basalt ____ Goldscl~midtand
Peters (1932).
Chalcopyrite, CuFeSs
Germany:
Clausthal --------------------- 20. 800 .1 Fifteen sam- Noddack and
pies. Nodc1ack (1931).
Breitenbrunn, near Zwickau ____ _ .2 100- ------------- Goldscl ""llidt and
1,000 Pete1·s (1932).
South Africa:
Transvaal, Rustenburg district __ <.5 <.5 ·------------- Schneic!=!rhohn and
Mori~z (1931).

Stannite, CusFeSnS,
England, Cornwall 2 100 .1 ------------- Noddack and
Noddack (1931).
6 100 .6 ------------- Goldsd·midt and
Do -------------------------
Peter~ (1932).
Czechoslovakia, Zinnwald ________ _ .2 100- ------------- Do.
1,000
Pyrrhotite, Fe1-xS
100 8 Noddac~ and
Norway, Fl1ysa 2
Nodd .. ~k (t '"131).
Germany, Biihl, near Kassel _____ _ .6 6 In basalt ___ _ Goldschmidt and
Pete1'" (1932).

South Africa, Transvaal ---------- 1-10 10-100 From Meren- Schnei(i"erhohn

sky Horizon (192S).
on Schild-
padnest,
Rustenburg
district.
Content of
other ele-
ments: Cu,
Co about 0.1
percent;
Pa, 10-100
ppm; Ru,
Rh, Ir, 0.1-
1 ppm; Os,
a trace.
4
 TABLE 2.-Analyses of precious metals in minerals made before 1955-Continued

Gold Silver Platinum

Mineral and locality (ppm) (ppm) (ppm) Remarks Reference

Sulfides, arsenides, selenides, and tellurides--Continued

Troilite, FeS
United States, Canyon Diablo, Ariz_ 0.5 10 0.5 In meteorite - Goldsclmidt and
Peter~ (1932).
Mexico:
Coahuila ---------------------- 1-5 5 1-10 _____ do _____ Do.
Ixtlahuaca --------------------- .2 15 6 _____ do _____ Noddack and
Nodcack (1931).
Chile, Corrizatillo _______________ _ .5 10 .2 _____ do _____ Goldscl midt and
Peters (1932).
Esthonia, Tennasilm 0 5 .3 _____ do _____ Noddar.k and
Nodc"ack (1931).
Niccolite, NiAs
Germany:
Eiselben _____________________ _ 1 1()..-100 Goldschmidt and
-------------
Pete~s (1932).
Klettenberg, Sauerland ________ _ 10 10 .2
Austria, Schladming, Styria ____ _
------------- Do.
•5 100 ------------- Do.
Pentlandite, (Ni,Fe,Co) eSs
Norway, Espedalen _____________ _ 6 140 2 Two samples - Noddack and
Nodrlack (1931).
Germany, St. Blasien, Schwarzwald_ .5 10-100 .2 ------------- Goldschmidt and
Pete~s (1932).
South Africa, Rustenburg district,
Transvaal --------------------- 1.0 5-10 ------------- Schnei/lerhohn and
Morftz (1931).
Siegenite, (Co,Ni)sS4
Germany, Miisen near Siegen ___ _ 1 >1,000 .5 ------------- Goldsc"midt and
Peters (1932).
Pyrite, FeS2
Norway:
Setesdalen .4 10 Fifteen sam- Nodda~k and
pies. Noddack (1931).
Sulitjelma --------------------- .4 70 .3 ------------- Do.
Italy:
Calceranica ------------------- 1.1 ------------- Mingur.zi (1947).
Libiola, Genova Province ______ _ .33 Two samples _ Do.
Boccheggiano, Grosseto _______ _ .12 ------------- Do.
Chuch e Servetie _____________ _ Do.
.95 ------------- Do.
Pestarena --------------------- 200 ----------------
Lavanchetto ------------------- 20 ---------------- Do.
6.5 Crystalline Do.
Alfenza -----------------------
aggregate
contained
12 ppm Au
and a crys-
tal con-
tained 0.93
ppm Au.
Two sam-
pies.
South Africa:
Rustenburg district, Transvaal __ _ 5-10 10-50 Nickeliferous_ Schne~<ierhohnand
Mo1.;tz (1931).
Witwatersrand 3 Three samples Hegenann and
Leybold (1954).
Sperrylite, PtAss
Canada, Vermillion mine, Ontario __ 40 300 >1,000 One sample __ N oddack and
N~dack (1931).

5
 TABLE 2.-Analyses of precious metals in minerals made before 1955-Continued

Gold Silver Platinum

Mineral and locality (ppm) (ppm) (ppm) Remarks Reference

Sulfides, arsenides, selenides, and tellurides--Continued

Cobaltite, CoAsS
Canada, Cobalt, Ontario _________ _ 6 6 0.1 ------------- Gold:-1~hmidtand
Pe+ers (1932).
Norway, Skutterud -------------- 10 200 2 One sample -- Nodcack and
Ncddack (1931).
.6 1 ------------- Gold:~ehmidt and
Pe~ers (1932).
Sweden, Tunaberg --------------- •6 10 .5 ------------- Do.
Germany:
Dreikonigsstollen Buchholz, Saxony •8 10 .1 ------------- Do •
Gliicksbrunn, Altenstein,
Sachsen-~eine --------------- 3 5 •1 ------------- Do•
Gersdorffite, NiAsS
Germany:
~lisen, near Siegen ------------ 10-100 10-100 .1 ------------- Do.
Friedensgrube, Lichtenberg,
Oberfranken ----------------- 10-100 10-100 .1 ------------- Do.
Lobenstein, Vogtland, Thiiringen_ 5 1 ------------- Do.
Michaelis Fundgrube, Triebel,
near Zwickau --------------- 10-100 10-100 .1 ------------- Do.
Ullmannite, NiSbS
Germany:
Miisen, near Siegen ------------ 20 20 •5 ------------- Do.
Salchendorf, near Siegen ______ _ 10 100- ------------- Do.
1,000
Landeskrone, Willnsdorf, near
Siegen ---------------------- .6 10-100 .2 ------------- Do•
Saffiorite, CoAs2
Germany:
Schneeberg, Saxony ------------ .8 10-100 ------------- Do.
Dachsberg, near Riechelsdorf 6 .5 •1 ------------- Do.
Rammelsbergite, NiAs2
Germany, Gessellschafter Zug,
Schneeberg, Saxony _________ _ .3 6 ------------- Do.
Marcasite, FeS2
Germany, Westphalia ____________ _ 4 100 .1 One sample __ Nodd~~k and
Nocdack (1931).
Arsenopyrite, FeAsS
Norway, Skutterud -------------- 8 90 •4 Four samples_ Do.
Germany, Ehrenfriedersdorf,
Saxony ----------------------- .6 10 ------------- Golds<'!hmidt and
Peters (1932) 0

Molybdenite, ~oS2
United States, Climax, Colo _____ _ .06 100 .05 ------------- Do.
Australia, Kingsgate, Glenn Innes,
New South Wales -------------- 1-10 100 •02 ------------- Do.
Czechoslovakia, Zinnwald ________ _ .1 .2 •05 ------------- Do.
Germany:
Sadisdorf near Schmiedeberg,
Saxony --------------------- 5 10-100 1 ------------- Do.
Altenberg, Saxony ____________ _ .2 2 .2 ------------- Do .
Norway:
Telemarken -------------------- .6 4 .04 Three samples Do.
Sorumsassen near Drammen ___ _ .6 10-100 .05 ------------- Do.
Rade, 0stfold _________________ _ •05 Do .
Undalen ______________________ _
10 -------------
.06 >100 With chalco- Do.
pyrite.

6
 TABLE 2.-Analyses of precious metals in minerals made before 1955-Continued

Gold Silver Platinum

Mineral and locality (ppm) (ppm) (ppm) Remarks Ref~renee

Sulfides, arsenides, selenid£s, and tellurides-Continued

Skutterudite, CoAss
Germany:
Niederrasmstadt near Darmstadt_ 0.3 1,000 Goldschmidt and
Peter"' (1932).
Riechelsdorf, Hessen _________ _ 2.7 10 Two samples _ Do.
Bieber, Hessen _______________ _ .1 1-5 Do.
Frauenbreitunger, Saxony-
]deiningen __________________ _
.8 10-100 Do.
Schneeberg, Saxony ___________ _ .5 100- Do.
1,000
Hasserode, Harz ______________ _ 5 10 Do.
Austria, Schladming, Styria ______ _ .8-.5 5 Do.

Sulfosalts

Tetrahedrite, CuuSb4S1s
England, Cornwall ______________ _ 8 >1,000 2 Noddack and
Noddack (1931).
Austria, Tyrol __________________ _ 60 >1,000 .2 Seven samples Do.
Germanite, Cua(Ge,Fe)S4
South-West Africa, Tsumeb -----~­ 40 800 .2 One sample __ Do.
Enargite, CuaAsS4
United States, Butte, Mont _____ _ 1& >1,000 .8 _____ do ____ _ Do.
Argyrodite, AgsGeSs
Bolivia -------------------------- 90 >1,000 0 _____ do ____ _ Do.

Halides

Halite, N aCl
England, Cheshire ______________ _ 0.103 N.D. N.D. Two samples_ Liversiige (1897).
Germany, Stassfurt _____________ _ .132 N.D. N.D. One sample __ Do .
Sylvite, KCl
Germany, Mecklenburg __________ _ .003 N.D • N.D. _____ do ----- Friedri ~k ( 1906) .
Carnallite, KMgdla: 6H20
Germany, Bernburg _____________ _ .012 N.D. N.D . ----- do ----- Do.

Simple oxides

Pyrolusite, Mn02
Czechoslovakia, Platten, Bohemia __ 0.2 4 10 Four samples_ Noddack and
Nodc.11ek (1931).
Cassiterite, SnOs
Bolivia, Potosi ------------------- .5 10-100 ·------------- Goldscl midt and
Pete:--s (1932).
Indonesia, Bangka Island ______ _ .5 10 ------------- Do.
Germany, Breitenbrunn near
Zwickau, Saxony ______________ _ .5 10 Three samples Do.
Czechoslovakia, Schonfeld near
Schlaggenwald ----------------- .5 5 ------------- Do.
South-West Africa:
Sandamab --------------------- .5 10 .2 ------------- Do.
Nubeb ------------------------ .5 1 •2 ------------ Do .

7
 TABLE 2.-A"'Z.alyses of precious metals in minerals made before 1955-Contm:ued

Gold Silver Platinum

Mineral and locality (ppm) (ppm) (ppm) Remarks Reference

Oxide!f eontainintr uranium, thorium, or zirconium

Uraninite, UOs
Norway, Brevik ------------------ 0.1 2 0.2 One sample __ N odd ""ek and
No·Jdack (1981).
Czechoslovakia, Jaehymov -------- .03 5 Two samples _ Do..
Thorianite, ThOs
Ceylon -------------------------- .05 2 •1 One sample -- Do•

Oxides C4ntainintr OB

Psilomelane, (Ba,HsO )sMnsOto

Germany, Harz ------------------ 50 2 Two samples _ Noddack and
Noddack (1981).

Multiple oxides

Chromite, (Mg,Fe)sCrO,
United States:
Mineral Hills, Pa -------------- 0.2 1 1 Golds~hmidt and
Pet1rs (1982).
Lancaster County, Texas, Pa __ _ .2 1 Do.
Norway, Feragen, Bebiet ---------- .2 1 Do.
Hausmannite, MnaO,
Sweden, Li.ngban ---------------- .1 10 Two samples _ Noddr~k and
Noc..fack (1981).

Multiple oxides eontainintr Nb, Ta, and Ti

Columbite, (Fe,Mn) (Nb,Ta)sOe

Norway, Arendal ---------------- 0.05 2 8 Twenty-three Nodd~ek and
samples. Nod~ack (1981).

Silieates

Plagioclase, (Na,Ca) (Al,Si)2Sb0s

South Africa, Rustenburg district,
<0.5 <0.5 Schnei~erhohn and
TransvaaJ ---------------------
Pyroxenes: Mor'tz (1981).
Bronzite, (Mg,Fe)SiOs
South Africa, Rustenburg district,
Transvaal --------------------- 1-5 Do.
Diallage, Ca(Mg,Fe)SisOe
South Africa, Rustenburg district,
Transvaal --------------------- .5 1-5 Do.
Olivine, (Mg,Fe)sSiO,
South Africa, Rustenburg district,
Transvaal --------------------- .5 1.0 Do.
Gadolinite, YsFeBe.SisOe
Norway, Iveland ----------------- .2 4 2 Nodda~k and
Noddack (19:ll)
Arandisite, (tin silicate?)
South-West Africa, Arandis _____ _ .5 5 .2 Goldsc:'tmi<~t
a'ld
Peters (1932).
Hellandite, silicate of Ca and Y
Norway, Kragero ---------------- .1 .1 One sample -- Noddaek and
Noddack (1981).

8
 TABLE 2.-Analyses of precious metals in minerals made before 1955-Continued

Gold Silver Platinum

Mineral and locality (ppm) (ppm) (ppm) Remarks R(>ference

Phosphates

Triplite, (Mn,Fe)J(PO.)F
South-West Africa, Sandamab ___ _ 0.5 5 0.2 ·------------- Goldschmidt and
Perers (1932).

Nitrates

Soda Niter, NaNOa

Chile --------------------------- 0.110 N.D. N.D. One sample -- Liversidge (1897).

Sulfates

Anhydrite, caso.
Germany, Pllimnitz -------------- 0.007 N.D. N.D. One sample-- Fried~ick 1906).
Gypsum, CaSO. ·2Hs0
United States:
Salina, N.Y ------------------- .083 N.D. N.D. Silurian. One Linco1n (1911).
sample.
Grand Rapids, Mich ------------ .083 N.D. N.D. Mississippian. Do.
One sample.
Kainite, KMg(SO.)Cl·SHsO
Germany, PIOmnitz --------------- •003 N.D. N.D• One sample __ Fried"ick (1906).

Both Anoshin and Potap'yev (1966) and in magnetite than in the silicat~ minerals.
Shcherbakov and Perezhogin (1964) show that Mantei and Brownlow accounted fc¥ the lower
the gold in the quartz exceeds that in the gold content of magnetite, comparee- with other
feldspars by a factor of 2.7. Shcherbakov and minerals they analyzed, by pointing out that
Perezhogin noted from the analyses of mono- the structure of magnetite is relatively closed
mineralic fractions of igneous rocks that the compared to the structures of biotite and horn-
average gold content decreases from magnetite blende and that "magnetite may bave formed
and ferromagnesian silicates to feldspars. They before the silicates, at a time wh~n the con-
reported (table 3) the gold content of the centration of gold in the magma was fairly
major rock-forming minerals as follows: low."
quartz, 11 ppb (parts per billion); feldspa~r, Badalov (1965) examined tl'~ average
4 ppb; biotite, 4 ppb; muscovite, 3.8 ppb; amounts of gold, silver, selenium, and tellurium
amphibole, 5.9 ppb; pyroxene, 16 ppb; olivine, in the disseminated copper-molybdonum depos-
14 ppb; and magnetite, 48 ppb. its of the Almalyk district in t\e U.S.S.R.
Mantei and Brownlow (1967) have made The sequence of the formation of the pre-
many neutron activation analyses of minerals dominate minem:ls in the ores was from earli-
from the Marysville quartz diorite stock (table est to llatest: magnetite, molybdenite, pyrite,
3). The diorite has an appreciably higher gold chalcopyrite, sphalerite, and galena. Pyrite is
content than the average diorite, and most by far the most abundant mineral and carries
of its component minerals have unusually high 3 ppm gold. Chalcopyrite is the :o;econd most
gold contents. The reported gold contents in- abundant mineral and was the chief "coneen-
crease from quartz and feldspar ( 65 ppb) trator" of gold; it contains 22 rpm. Native
to biotite (76 ppb) and reach a maximum gold is common, and gold tellurid ~s are rare.
in hornblende (100 ppb). The gold content N oddack and N oddack ( 1931) looked for
of magnetite was found to be only 37 ppb, but did not detect gold in the for owing min-
in contrast to the findings of Shcherbakov erals: allanite, alvite (variety of zircon), an-
and Perezhogin ( 1964) who report more gold dalusite, 1aragonite, beryl, brewster~te, bronzite,

9
 TABLE 3.-Analyses of gold in minerrals made since 1954
[Minerals containing higher amounts of gold are listed in table 1]

Gold
Mineral and loeality (ppm) Remarks

Elements

Arsenolamprite, As
Germany, Thuringia 5 Silver, 1 ppm. Spectographic an- Fischer (1958-59).
alysis.
Iron, (Fe, Ni)
U.S.S.R., Sikhote-Alin' _________ _ 1.15 One sample of meteorite. In troilite. ShcheJ·bakov and
0.067 ppm Au. Neutron activation Perczhogin
analysis. (19fi4).

Snlftdes

Arsenopyrite, FeAsS
U.S.S.R., Central Chukotki ______ _ 200 Samples from veins and ore miner- Sidoro":r (1966).
als.
Germany, Thuringia .5 Silver, 15 ppm. Spectrographic an- Fischer (1958-59).
alysis.
Chalcopyrite, CuFeSs
U.S.S.R., Almalyk .22 Chalcopyrite is the chief "concen- Badalc~r (1965)
trator" but pyrite is ·the chief and Badalov and
"carrier." Content in parts per Tere.khovich
million of Pd, 0.21, Pt, 0.02, Ag, (196~).
0.02. Analyses by fire assay fol-
lowed by spectrographic.
Germany, Thuringia .02 Pd, 0.2 ppm, Ag 10- 3percent. Spec- Fische~ (1958-59).
trographic analysis.
Cobaltite, CoAsS
Germany, Thuringia 5 Silver, 20 ppm. Spectrographic an- Do.
alysis.
Galena, PbS
U.S.S.R:
Central Chukotki _____________ _ 5 Sidoro,. (1966).
Almalyk ---------------------- 13 Silver, 450 ppm. Pd, 0.032 ppm. Badalo"• and
Analyses by fire assay followed Tere1rhovich
by spectrographic. (1961i).
Germany, Thuringia .01 Silver, 29-100 ppm. Spectrographic Fische1· (1958-59).
analysis.
Molybdenite, MoSs
Germany, Thuringia .02 Content in parts per million of: Ru, Do.
0.03, Rh, 0.4, Pd, 0.6, Pt, 0.4, Ag.
>lo-s percent.
Pyrite, FeSt
East Greenland ------·------------ .016 Vincen-4: and
U.S.S.R: Crocket (1960).
Almalyk ---------------------- 3 Content in parts per million of: Ag, Badalon ( 1965).
60, Se, 40, and Te, 16. Pyrite is
the chief "carrier" but chalcopy-
rite is the chief "concentrator" of
gold.
Do 3.5 Silver, 36 ppm, Pt, 0.014 ppm. An- Badalo"r and
alyses by fire assay followed by Terel~hovich
spectrographic. (196f).
Central Chukotki -------------- 10 Samples from veins and ore min- Sidorov (1966).
erals.
Gennany, Thuringia ____________ _ .2 Silver, 5 ppm. Spectrographic an- Fischer (1958-59).
alysis.

10
 TABLE 3.-Analyses of gold in minerals made since 1954-Continued

Mineral and locality Gold :B~ference

(ppm) Remarks

Sulfid-<1ontinued

Pyrrhotite, Fet-xS
East Greenland _________________ _ 0.003 Analyses by neutron activation ___ _ Vince:-1t and
Cro~ket (1960).
U.S.S.R., Central Chukotki ______ _ 2 Samples from veins and ore min- Sidorov (1966).
erals.
Sphalerite, (Zn, Fe) S
U.S.S.R., Central Chukotki ______ _ 500 ________________ do Do.
Stibnite, SlnSa
U.S.S.R., Central Chukotki ______ _ 20 ________________ do ______________ _ Do.
Germany, Thuringia ____________ _ .9 Silver, 2 ppm. Spectrographic an- Fischer (1958-59).
alysis.
Troilite, FeS
United States:
Canyon Diablo, Ariz .10 One sample of meteorite. Analysis Baede.~ker (1967).
by neutron activation.
Sardis, Ga -------------------- .23 One sample of meteorite found in Do.
rocks of Miocene age. Analysis
by neutron activation.
U.S.S.R., Sikhote-Alin' __________ _ .67 One sample of meteorite. The iron Shcherbakov and
part of this meteorite contained Per~hogin
1.15 ppm Au. (19,~4).

Ullmanite, NiSbS
Germany, Thuringia 1 Silver, 10 ppm. SpectrogTaphic an- FisCher (1958-59).
alysis.

Sulfosalts

Tetrahedrite, Cu12Sb4S1a
Germany, Thuringia 0.02 Silver, 20-100 ppm. Spectro- Do.
graphic analysis.

Oxides

Magnetite, FeaO•
United States, Helena, Mont ----- 0.037 Forty-four samples from the Manwi and
Marysville quartz diorite stock, Brownlow
20 miles northwest of Helena, (19r,7).
Mont. Fifty-one analyses made
of these samples which ranged
in gold from 0.003 to 0.329 ppm.
Analyses by m~utron activation.
U.S.S.R., Altai-Sayan folded belt (?) .048 Seven samples. Analyses by neu- Shche...bakov and
tron activation. Per?.zhogin
(19r,4).
Pyrolusite, Mn02
Germany, Thuringia Silver, 3 ppm. Spectrographic an- FisCher (1958-59).
alysis.
Quartz, Si02
U.S.S.R.:
Central Chukotki _____________ _ 2 Samples from veins and ore miner- Sidorov (1966).
als.
Altai and Transbaikal _________ _ .0008 Analyses by neutron activation. AnosUn and
Potap'yev
(1966).
Altai-Sayan folded belt ( ?) ____ _ .011 Analysis by neutron activation. Shche...bakov and
Nine samples. Per~hogin
(19r,4).

11
 TABLE 3.-Analyses of gold in mi:nerals made since 1951,-Continued

Gold
Mineral and loeality (ppm) Remarks R'!ferenee

Oxides-Continued

Quartz and feldspar

United States, Helena, Mont_____ _ 0.065 TEm samples from the Marysville Mante~. and
quartz diorite stock, 20 miles Brm..,Uow
northweSt of Helena, Mont. (1967).
Twelve analyses made of these
samples which ranged in gold
from 0.006 to 0.176 ppm. An-
alyses by neutron activation.
Wad, Mn oxide
Germany, ThUringia Silver, 5 ppm. Spectrographic an- Fischer (1958-59).
alysis.

Silicates

Feldspars, AI ,silicates with K, Na, and

Ca
U.S.S.R., Altai-Sayan folded
belt (?) ---------------------- 0.0040 Twenty-seven samples. Analyses by Shcher'-lakov and
neutron activation. Perel;hogin
(1964).
Altai and Transbaikal ----------- .0003 Analysis by neutron activation. Anoshi"' and
Pota:o'yev
(1966).
Microcline, KAISiaOs
U.S.S.R., S. E. Altai ------------- .018 One sample from a migmatite. An- Shcherhakov and
alysis by neutron activation. Pere?.hogin
(19M).
Amphiboles, hydrous silicates with
chiefly Ca, Mg, Fe, AI, and N a
U.S.S.R.:
Altai-Sayan folded belt ( ?) •0059 Fourteen samples analyzed by Do•
neutron activation method.
Kuznetsk, Ala-Tau ------------- •077 Two samples analyzed by neutron Do.
activation.
Hornblende, CatNa(MgFeH)4 AI,
Fe +3 Ti) aSisOn (O,OH) 2
United States, Helena, Mont. ____ _ .100 Thirty-seven samples from the Mantei and
Marysville quartz diorite stock, Brownlow
20 miles northwest of Helena, (1967).
Mont. Forty-two analyses made
of these samples which ranged
in gold from 0.003 to 0.823 ppm.
Analyses by neutron activation.
Pyroxene, silicates of Ca, Mg, Fe, and
others
U.S.S.R., Altai-Sayan folded
belt (?) ---------------------- .016 Eight samples analyzed by neutron Shcherbakov and
activation. Perezhogin
(1964).
Tourmaline, complex silicate of B and
AI
U.S.S.R., Altai-Sayan folded
belt (?) ---------------------- .012 Four samples analyzed by neutron Do.
activation.
Muscovite, KAlt (AI Sis) Oto(OH)J
U.S.S.R., Altai-Sayan folded
belt (?) ---------------------- .0038 Seven samples analyzed by neutron Do.
activation.

12
 TABLE 3.-Analyses of gold in minerals made since 1954-Continued

Gold
:Mineral and locality (ppm) Remarks Refnrenee

Silicates-Continued

Biotite, K(Mg, Fe)s(AlS6) Oto(OH)I

United States, Helena, Mont _____ _ 0.076 Forty-four samples from the Mantei and
Marysville quartz diorite stock, Brownlow
20 miles northwest of Helena, (1967).
Mont. Fifty-three analyses made
of these samples which ranged
in gold from 0.002 to 0.924 ppm.
Analyses by neutron activation.
U.S.S.R., Altai-Sayan folded
belt (?) ---------------------- .0040 Eight samples analyzed by neutron Sheher't'f-tkov and
activation. Perezhogin
(1964).
Altai --------------------------- •0091 Three samples from granite which Do.
were analyzed by neutron acti-
vation.
Olivine, (Mg,Fe)sSi04
U.S.S.R., Altai-Sayan folded
belt (?) ---------------------- .014 Two samples analyzed by neutron Do.
activation.
Sphene, CaTiSiOs
U.S.S.R., Altai-Sayan folded
belt (?) ---------------------- .0039 Two samples analyzed by neutron Shcherl1.kov and
activation. Perexhogin
(1964).

cristobalite, daubreelite (from meteorites), di- Detected in 90-100 percent of

opside, epidote, euclase, garnet, gersdorffite, the samples ------------------Ag, Cu, f'e
Detected in 18.8-37.6 percent of
harmotome, hauerite, heulandite, hornblende, the samples ------------------Ph, Ti, Al, Sb, Hg,
kaolin, lepidolite, leucite, malachite, malacon, V, Bi, Mn, Si, As,
molybandocker [ilsemannite], molybdosodalite, Sn
muscovite, nepheline, olivine, orpiment, ortho- Detected in 6.3-14.6 percent of
clase, pyroxene, rhodochrosite, rutile, serpen- the samples __________________ Mg, Ni, Ca, Zn,
Pd, Pt, Te
tine, stibnite, tantalite, thalenite, and thort- Detected in 2.1-4.2 percent of
veitite. The lower limit of detection of the the samples __________________ B, Co, C1·, Mo, Cd,
analytical method they used seems to be about Rh, Sr, W, Zr
10 ppb. Other specimens of some of these It is probable that not all the elements in the forego-
minerals analyzed by neutron activation meth- ing list were looked for by most analysts.
ods also show less than 10 ppb Au (table
3). Warren and Thompson (1944) studied the
Platinum exceeds gold in meteorites, as well composition of 66 samples of native Jr">ld, about
as in metasilicate minerals and orthosilicate 75 percent of which originated ir Canada.
minerals. All samples contained silver, copper~ and iron.
The number of occurrences of the varous other
COMPOSITION AND THE FINENESS OF GOLD elements in the gold were: titanium. 52~ mer-
Samples of native gold from 48 places cury, 42: manganese, 40~ lead, 37; vanadium,
throughout the world have been analyzed for 28: tin, 22: antimony, 21; bismuth, 19r arsenic,
selected elements (Gay, 1963). The frequency 17~ zinc, 1&, cadmium, 14, tellurium. 8: plati-
of occurrence of 30 elements detected (in order num, 3t and palladium, 2. Silver w".c; usually
of frequency) is as follows: present in amounts exceeding 0.5 p~rcent and

13
copper was usually present in amounts from that this seemed to indicate that the deposits
0.1 percent to 0.5 percent. The remaining ele- were formed by diffusion of gold and silver
ments, when present in the gold, were usually through the cou.ntry rock. For instance, in
in amo'Jnts of less than 1 percent. the Yellowknife district of Cans da, gold -in
deposits in greenstone has a gold~silver ratio
Wise (1964), in a study of binary alloys
of 5:1 ( = fineness 833), whernas gold in
of gold, gives the various maximum high-tem- quartz lenses in sedimentary rocks has a ratio
perature solid solubilities of elements in gold of 3.5:1 ( = fineness 778). Ward observed
as follows: that gold in some ore bodies in '\\~estern Aus-
100 percent ____________________ Ag, Cu, Ni, Pd, Pt tralia that are genetically relatr1 to albite
46 percent _--------------------Fe porphyry intrusives has a gold to silver ratio
21.5---19 percent _______________ Cd, Cr, Hg
greater than 9:1 ( = fineness 9(1). Lincoln
13 percent --------------------- Zn
10.9-7.7 percent _______________ Mn, Ta, Co, In noted that the fineness of gold i~ higher in
5.2-1.2 percent ________________ V, Ga, Sn, Mg, AI, silicic igneous rocks than in maf~ varieties;
Ti, Ge gold in silicic igneous rocks aver? ~es 979 in
<1 percent --------------------As. Bi, Ca, Mo, Pb, fineness, that in intermediate typ~s 451, and
Pr, Rh, Sb, Th,
Tl, U, and per-
that in mafic types 245.
haps others. Native gold at the surface and in the oxidized
The fineness of gold, and especially its rela- zone of a mineral deposit is usuall:.. finer than
tion to the genesis of gold denosits. has been is the native gold in the unoxidizei ore (Don,
studied by numerous workers (Gay, 1963; Sun- 1898; Fisher, 1945; Colin, 1946; MacGregor,
dell, 1936; Mertie, 1940). Fineness refers to 1928; Mackay, 1944; Mills, 1954. and Gay,
the ratio of gold to the sum of the gold plus 1963). Below the oxidized zone, hc~~ever, gold
fineness seems to be largely ind~pendent of
the silver in the naturally occurring alloys
depth (Gay, 1963). A small decr~ase in the
and is defined as 1,000 times Au/(Au+Ag). fineness of gold with depth in the. Lily mine,
Me:rtie (1940) noted that pure gold has not Republic of South Africa, is reported by An-
been found in nature, but that gold is always haeusser (1966) and shown in 1able 4. On
alloyed with silver and a small amount of the other hand, average gold fine~ess in the
the base metals such as iro.n and copper. The Zwartkopje shoot in the Sheba mine, Repub-
purest gold reported by Mertie was from the lic of South Africa, increases with depth from
Great Boulder mine, in the Kalgoorlie district the 14 level (about 910 fine) to 1he 26 level
of Western Australia; it was 999.1 fine. Mertie (about 950 fine) within a vertical distance
of about 550 feet (Gay, 1964).
concluded that fineness is rarely less than 600
and is generally never less than 400, although TABLE 4.-Variations in fineness of gold with depth,
Lincoln (1911) reported a fineness of 246 for Lily Mine, Transvaal, South Africa
· silver-gold alloys in some mafic igneous rocks. [After Anhaeusser, 1966]

The color of gold in polished section is an Depth

in feet
index of its fineness, according to Eales (1961). below
2,600-foot
Nearly pure gold has a golden color with a Level
datum Gold
plane (percent)
Silv·~r
(percent·) Fineness
ruby tint. With increasing amounts of silver, 70-foot ______ . _ ---- 200 91.50 8.50 915
the color changes to yellow and eventually 1 ----- ·--- ---·------
1% _.. -------- -- - --- ---
260
340
91.15
90."8
8.85
9 72
911.5
903
becomes ~ pale silvery yellow color as in elec- 2-----------------. 420 89.04 10.96 890

trum. Others have noted color differences in

gold due to variations in fineness (Mather, Gold fineness was noted by Gay (1963) to
vary from east to west in some Witwatersrand
1937; Russell, 1929; Edwards, 1958).
deposits as follows: 865.8, 884.0, 870.6, 926.0,
Boyle (1960), Ward (1958), and Lincoln 912.0, 924.0, and 970.0. Sharwood (1911) re-
(1911) have commented on the fineness of ports some lateral variation in fineness of bul-
gold in different country rocks. Boyle thought lion from mines in the Lead district, South
that the fineness of gold in lode deposits re- Dakota; as shown in table 5, the range in
flected the nature of the country rock and fineness is small.

14
TABLE 5.-Fineness, in percent, of mill bullion prior to the gold. Shcherbina (1956) explains that the
1882 at the Homestake mine, South Dakota high ratio of silver to gold, 37J\ (Mason,
[Sharwood. 1911]
1952) in sea waters, compared to only about
Base 10 (Vinogradov, 1956) for the lith9sphere as
Mine Gold Silver metal' Fineness
a whole, is an indication of the gre~.ter mobil-
Homestake ____________ 82.0 17.0 1.0 828
Highland ______________ 83.0 15.5 1.5 843 ity of silver.
Terra ______________ 82.5 16.0 1.5 838
Deadwood ______ ------- 85.0 14.0
17.0
1.0
1.0
859
828
Mertie (1940) says that in sotro. Alaskan
De Smet -------------- 82.0
paystreaks the fineness of gold incre.q,ses down-
Lateral variation in fineness is shown by stream from its source, but in others the fine-
analyses of the bullion from nine representa- ness changes either erratically or not at all.
tive mines in Gilpin County, Colo. (Collins, He cites an Alaskan placer gold d~posit that
1902). During the period 1870 to 1880, the was derived from lodes in Tertiary quartz
fineness ranged from mine to mine from 753 monzonite. The source lodes were being actively
to 897, and during the period 1880 to 1890, mined around 1940, and informat~0n on the
from 716 to 894. The average fineness of all fineness of both lode and placer gold indi-
the bullion from these mines changed little cates that the fineness does not increase pro-
during the two periods; it was 799 for the gressively downstream.
first and 789 for the second. Fineness varies not only from gr8.in to grain
Eales (1961) studied the silver content of but also w.jthin graillls (Gay. 1963). Some
gold from four hydrothermal deposits in grains are finer in the center than on the
Southern Rhodesia. Gold that mineragraphic surface (Head, 1935), although Er.les (1961)
studies show to have crystallized early, and has noted the reverse. Gold extrac~ed by Mc-
that is enclosed in chalcopyrite and sphalerite, Connell (1907) from the outer surface of a
contains more silver than does gold that crys- nugget assayed 60-70 parts per tho~lsand finer
tallized later. than gold from the inside of the rugget, and
The fineness of gold varies directly with his findings have been cited as evidence that
particle size in some deposits and inversely surface waters dissolve an appreciable amount
with particle size in others (Gay, 1963). of silver from alluvial gold. However, the dif-
ference could have been due to the original
For ore deposits in general, the fineness character of the primary lode gold or to sur-
of the contained gold increases as the grade of
ficial enrichment of the gold in the zone of
ore increases; (Eales, 1961; Lawn, 1924; Mac--
oxidation before it was freed (Mertie, 1940).
Gregor, 1928; and Mackay, 1944).
Very fine grained placer gold is u~ually finer
Fisher ( 1950) concluded that fineness used than the coarse gold (Hite, 193~; Sundell,
with other criteria furnishes a sensitive and 1936; Fisher, 1945; and Colin, 1~46). How-
reliable guide to the relative temperature of ever, Mertie (1940) reports that in any one
ore formation, at least within the epithermal
paystreak, and at any o.ne place in the pay-
and the upper part of the mesothermal range
streak, the reverse is usually true.
of temperatures. The fineness of epithermal
gold is from 500 to 700. Near the bottom
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15
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