Rocks Minerals Notes Kean University
Rocks Minerals Notes Kean University
Rocks Minerals Notes Kean University
Introduction
Atoms & Elements
Minerals
Igneous Rocks
Sedimentary Rocks
Metamorphic Rocks
The Rock Cycle
Geology of Mineral Resources
Summary
Introduction
Think about it . . .
1. Where is the nearest outcrop of bedrock?
2. Where is the nearest example of a rock that is not part
of the local bedrock?
3. Give three examples of how minerals and/or rocks are
used in your daily life?
O2Si4+
Al3+
Fe2+, Fe3+
Ca2+
Na+
K+
Mg2+
-
46.6
27.7
8.1
5.0
3.6
2.8
2.6
2.1
1.5
Think about it . . .
1. The atomic number of carbon is six. How many
protons are present in the nucleus and how many
electrons are in the atoms outer shell?
2. Four elements and their atomic numbers are listed
below. Which has a stable atomic configuration?
a) Hydrogen (1)
c) Magnesium (12)
b) Neon (10)
d) Calcium (20)
3. Calciums atomic number is 20: Will it form an anion
or cation?
4. Rock salt is formed by ionic bonding between Sodium
(Na, atomic number 11) and chlorine (Cl, atomic
number 17). What is the chemical formula for rock
salt?
Minerals
Figure 7. Quartz
crystals form
prisms; columns
with pyramids at
either end.
Mineral Characteristics
Although there are thousands of minerals in Earth, there are
only about 20 common minerals. The same mineral found in
different parts of the world will always look the same and will
have a characteristic crystal form and a consistent chemical
formula. Minerals can be identified in rocks by a process of
elimination. A variety of features can be used to identify
specific minerals. Some of the most common are listed below.
Crystal Form
Minerals form crystals with specific shapes (Fig. 8) when they
have been able to grow without obstruction. Common shapes
Figure 8. A range of
crystal shapes
including pyramid
(calcite, left) and
acicular (needlelike, tourmaline,
right).
Softest
Hardest
Color
Minerals come in a variety of colors (Fig. 11). Examples of
common dark-colored minerals (black, dark brown, dark green)
are amphibole, olivine, pyroxene, biotite mica. Light-colored
minerals (white, pink, gray, translucent) are represented by
quartz, feldspar (orthoclase, plagioclase), muscovite mica,
gypsum, halite, calcite. However, we must be careful in using
color to identify minerals because some minerals can be found
in a wide range of colors.
Luster
Characteristics of light reflected from
mineral is luster (Fig. 12). Types of
luster include earthy, silky, glassy,
and metallic.
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Figure 9. Cleavage
planes in amphibole
intersect at an angle of
120 degrees.
Figure 10.
Corundum ranks
9th on Moh's
hardness scale
Streak
Minerals will leave a mark when pulled across an unglazed
porcelain streak plate (Fig. 13). The streak represents the
mineral in powdered form and is often constant even when
mineral color changes. This property is most useful for
metallic minerals that leave a dark-colored streak.
Other
Calcite reacts (bubbles) with weak acids (Fig. 14); halite (rock
salt) has a salty taste.
Figure 14. Left:
Calcite and
dropper prior to
addition of acid.
Right: Reaction of
calcite and weak
hydrochloric acid.
Think about it . . .
Finish the partially completed concept map for
minerals found at the end of the chapter. Fill in
the blanks with appropriate terms.
Igneous Rocks
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12
Volcanic
Rocks
Basalt
Andesite
Rhyolite
Gabbro
Diorite
Granite
Plutonic
Rocks
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Volcanic Rocks
Plutonic Rocks
High
Rhyolite
Granite
Intermediate
Andesite
Diorite
Low
Basalt
Gabbro
Think about it . . .
1. Is there any significant difference in the way we
classify igneous rocks and the objects in the image
below?
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Sedimentary Rocks
15
16
Rock
Clay
Shale, Mudstone
Silt
0.0039 to 0.0625 mm
Siltstone
Sand
Gravel
0.0625 to 2 mm
More than 2 mm
Sandstone
Conglomerate
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Think about it . . .
What observations can you make about the image below that
would help make an interpretation of the origin of the pictured
sediments?
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Relative
proportion of
sedimentary
rock types
Clastic
sedimentary
rocks:
86%
Chemical and
biochemical
sedimentary
rocks:
14%
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Think about it . . .
Make a concept map for sedimentary rocks using the
terms here. Generate your own linking phrases that
connect these terms together.
clastic rocks
gravel
streams
biochemical rocks
lithification
precipitation
weathering
chemical rocks
deposition
grain size
sedimentary rocks
living organisms
Metamorphic Rocks
Contact Metamorphism
Contact metamorphism occurs when rocks undergo
metamorphism because they come in contact with a heat source
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Regional Metamorphism
Regional metamorphism occurs when rocks undergo increased
temperatures and pressures and is typically associated with the
formation of mountain belts. In these areas rocks may be
buried to great depths (10-20 km).
The additional pressure causes tabular minerals (e.g., mica) in
the rock to grow parallel to each other and perpendicular to the
direction of pressure (stress), generating a mineral alignment
termed foliation (Fig. 25)
Increased temperatures and/or pressures generate more intense
grades of metamorphism. Foliated metamorphic rocks in order
of increasing metamorphic grade (low to high temperature) are
slate, phyllite (Fig. 26), schist, and/or gneiss (Fig. 27).
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Think about it . . .
Make a concept map that summarizes the characteristics
of metamorphic rocks.
Figure 28.
A summary
diagram of
the rock
cycle.
Think about it . . .
1. Use the Venn diagram at the end of the chapter to
compare and contrast the similarities and differences
between igneous, sedimentary, and metamorphic
rocks.
2. Complete the diagram of the rock cycle at the end of
the chapter by filling in the blanks.
3. Describe how you might use beach sands to
understand the geology of a landmass surrounded on
several sides by ocean.
Introduction
A rock containing economic concentrations (reserves) of
metallic minerals is known as ore. Noneconomic minerals
(e.g., quartz, feldspar, calcite) found in association with ore
minerals are known as gangue (pronounced "gang") and are
considered waste. The average concentration of minerals in the
crust is insufficient to form an ore. Various geologic processes
(see below) concentrate minerals within the crust.
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Summary
1. How do rocks on Mars compare to those on Earth?
The rocks, and the minerals they contain, provided clues to the
evolution of the planet. Rocks on Mars were determined to
have a composition similar to andesite, a common igneous rock
on earth.
2. What is the relationship among atoms, elements, and
minerals?
Rocks are made up of minerals. Minerals can be divided into
their constituent elements. Elements cannot be further divided
into other materials but they can be separated into individual
atoms, the smallest particles that retain the characteristics of
the element.
3. What are protons, neutrons, and electrons?
Atoms are composed of neutrons, protons, and electrons. The
protons and neutrons are present in the atoms nucleus which is
surrounded by electrons.
4. What is an ion?
Atoms may loose or gain electrons to reach a more stable
configuration. This results in the formation of a negatively or
positively charged atom known as an ion. Ions may be either
positive (cation) where an atom has lost electrons, or negative
(anion) where an atom has gained electrons.
5. What are the most common elements in the continental
crust?
Eight elements (oxygen, silicon, aluminum, iron, calcium,
magnesium, sodium, potassium) make up more than 98% of
the continental crust.
6. What are silicates?
The most common minerals are composed of the most common
elements. Silicon and oxygen make up over 70% of the
continental crust by weight; minerals that contain both silicon
and oxygen are known as silicates.
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28. What are the most valuable mineral resources in the U.S.?
Annual production of crushed stone, cement, and sand and
gravel ($5.1 to 8.6 billion) are all worth more than the annual
value of precious metals such as gold ($4 billion). Copper and
gold are the most valuable metallic resources.
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Igneous Rocks
Metamorphic Rocks
Sedimentary Rocks
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