Attached you will see 4 labs – Lab 3 on Minerals, Lab 4 on Igneous Rocks, Lab 5 on Sedimentary Rocks, and Lab 6 on Metamorphic Rocks. I numbered them this way so that they match our course; however, I took some materials from a textbook I found online which have the lab numbers a bit different. Please ignore the numbers within the documents (for example, if you click on what I labeled as Lab 5 you’ll see that it says Lab 6 on the first page. Treat it as Lab 5).
Also attached you’ll see some rock or mineral charts. These are what I want you to fill out for the lab portion. You’ll have to identify some rocks or minerals and record their properties according to the terms discussed in the lecture section of the class and in the lab reading. The documents that are not rock or mineral charts contain extra information that may help you with the lab; however, you do not need to complete any activities you may see at the end of them.
Here are the links you’ll need to identify the rocks and minerals online for the lab assignments:
Lab 3 Minerals Website –
https://omg.georockme.com/unknown-samples
Lab 4 Minerals Website –
https://igg.georockme.com/unknowns
Lab 5 Minerals Website –
https://seg.georockme.com/unknowns
Lab 6 Minerals Website –
https://meg.georockme.com/unknowns
*You’ll notice that for each sample in the website they have videos of some important tests so you can identify the mineral or rock
Here are the samples you’ll be identifying:
Lab 3 Minerals to Identify – A1 , A3 , A4 , A5 , A6 , A7 , A8 , A9 , A13 , A14 , A15 , A18 , A19 , A20 , A25 , A28 , A29
Lab 4 Rocks to Identify – A01, A02, A03, A05, A07, A08, A10, A12, A16
Lab 5 Rocks to Identify – A01, A02, A03, A04, A05, A06, A07, A08, A09, A11
Lab 6 Rocks to Identify – A01, A02, A03, A04, A05, A06, A07, A08
5.8 Analysis and Interpretation of Igneous Rocks
IGNEOUS ROCKS WORKSHEET
Sample
Number
or Letter
Texture(s) Present
(Figure 5.4)
Minerals Present and
Their % Abundance
(Figure 5.4)
Mafic Color
Index
(Figure 5.5)
Rock Name
from
Figure 5.4 or 5.5
How Did the Rock Form Relative to
Bowen’s Reaction Series (Figure 5.6)
and Intrusive/Extrusive Processes?
Name: ______________________________________ Course/Section: ______________________ Date: ___________
150
ACTIVITY
Sample
Number
or Letter
Texture(s) Present
(Figure 5.4)
Minerals Present and
Their % Abundance
(Figure 5.4)
Mafic Color
Index
(Figure 5.5)
Rock Name
from
Figure 5.4 or 5.5
How Did the Rock Form Relative to
Bowen’s Reaction Series (Figure 5.6)
and Intrusive/Extrusive Processes?
151
Name: ______________________________________ Course/Section: ______________________ Date: ___________
IGNEOUS ROCKS WORKSHEET
7.3 Hand Sample Analysis, Classification, and Origin
METAMORPHIC ROCKS WORKSHEET
Sample
Letter or
Number
Texture(s)
(Figure 7.16—Step 1)
foliated
nonfoliated
foliated
nonfoliated
foliated
nonfoliated
foliated
nonfoliated
foliated
nonfoliated
Mineral Composition and Other
Distinctive Properties
(Figure 7.16, Step 2)
Rock Name
(Figure 7.16, Step 3)
Parent Rock
(Figure 7.16, Step 4)
Uses
(Figure 7.16, Step 5)
Name: ______________________________________ Course/Section: ______________________ Date: ____________
ACTIVITY
ACTIVITY
MINERAL DATA CHART
Luster*
Hardness
Cleavage
Color
Streak
105
*M = metallic or submetallic, NM = nonmetallic
Fracture
Other notable properties;
tenacity, magnetic attraction, reaction
with acid, specific gravity, smell, etc
Name (Fig. 3.18, 3.19, or 3.20)
and chemical composition
(Fig. 3.21)
How do you depend on this mineral
or elements from it?
(Fig. 3.21)
Name: ______________________________________ Course/Section: ______________________ Date: ____________
Sample
Letter or
Number
3.4 Mineral Analysis, Identification, and Uses
MINERAL DATA CHART
Luster*
Hardness
Cleavage
Color
Streak
*M = metallic or submetallic, NM = nonmetallic
Fracture
Other notable properties;
tenacity, magnetic attraction, reaction
with acid, specific gravity, smell, etc
Name (Fig. 3.18, 3.19, or 3.20)
and chemical composition
(Fig. 3.21)
How do you depend on this mineral
or elements from it?
(Fig. 3.21)
Name: ______________________________________ Course/Section: ______________________ Date: ____________
106
Sample
Letter or
Number
MINERAL DATA CHART
Luster*
Hardness
Cleavage
Color
Streak
107
*M = metallic or submetallic, NM = nonmetallic
Fracture
Other notable properties;
tenacity, magnetic attraction, reaction
with acid, specific gravity, smell, etc
Name (Fig. 3.18, 3.19, or 3.20)
and chemical composition
(Fig. 3.21)
How do you depend on this mineral
or elements from it?
(Fig. 3.21)
Name: ______________________________________ Course/Section: ______________________ Date: ____________
Sample
Letter or
Number
MINERAL DATA CHART
Luster*
Hardness
Cleavage
Color
Streak
*M = metallic or submetallic, NM = nonmetallic
Fracture
Other notable properties;
tenacity, magnetic attraction, reaction
with acid, specific gravity, smell, etc
Name (Fig. 3.18, 3.19, or 3.20)
and chemical composition
(Fig. 3.21)
How do you depend on this mineral
or elements from it?
(Fig. 3.21)
Name: ______________________________________ Course/Section: ______________________ Date: ____________
108
Sample
Letter or
Number
Sample
Number
or Letter
Composition
(Figures 6.2 and 6.9)
Textural and Other Distinctive
Properties (Figures 6.3 and 6.9)
Rock Name
(Figure 6.9)
How Did the Rock Form?
(See Figure 6.10)
Name: ______________________________________ Course/Section: ______________________ Date: ____________
180
SEDIMENTARY ROCKS WORKSHEET
BIG IDEAS
PRE-LAB VIDEO
Minerals comprise rocks and are described and classified
on the basis of their physical and chemical properties.
Every person depends on minerals and elements refined
from them, but the supply of minerals is nonrenewable,
and the magnitude of their use may be unsustainable.
FOCUS YOUR INQUIRY
|
THINK What are minerals and crystals, and how are they
About It related to rocks and elements?
ACTIVITY 3.1 Mineral and Rock Inquiry (p. 74)
THINK
About It
| How and why do people study minerals?
ACTIVITY 3.2 Mineral Properties (p. 77)
ACTIVITY 3.3 Determining Specific Gravity (SG) (p. 86)
THINK How and why do people study minerals? How do
About It you personally depend on minerals and elements
extracted from them?
L A B O R ATO R Y
3
Mineral Properties,
Identification,
and Uses
ACTIVITY 3.4 Mineral Identification and Uses (p. 88)
THINK How do you personally depend on minerals and
About It elements extracted from them? How sustainable
is your personal dependency on minerals and
elements extracted from them?
ACTIVITY 3.5 The Mineral Dependency Crisis (p. 89 )
THINK How sustainable is your personal dependency
About It on minerals and elements extracted from them?
ACTIVITY 3.6 Urban Ore (p. 99)
CONTRIBUTING AUTHORS
Jane L. Boger • SUNY, College at Geneseo
Philip D. Boger • SUNY, College at Geneseo
Roseann J. Carlson • Tidewater Community College
Charles I. Frye • Northwest Missouri State University
Michael F. Hochella, Jr. • Virginia Polytechnic Institute
Bingham Canyon Mine, southwest of Salt Lake City, Utah. It is
primarily a copper mine, but gold, silver, and other metals have also
been extracted from the ore here for over a century. (Michael Collier)
73
ACTIVITY
3.1 Mineral and Rock Inquiry
THINK
What are minerals and crystals, and how
About It are they related to rocks and elements?
OBJECTIVE Analyze rock samples, and infer how
minerals are related to and distinguished from rocks,
crystals, and chemical elements.
PROCEDURES
1. Before you begin, do not look up definitions and
information. Use your current knowledge, and
complete the worksheet with your current level
of ability. Also, this is what you will need to do
the activity:
____ Activity 3.1 Worksheet (p. 101) and pencil
2. Then answer every question on the worksheet
in a way that makes sense to you and be
prepared to compare your ideas with others.
3. After you complete the worksheet, read about
minerals and rocks below and be prepared to
discuss your observations, interpretations, and
inferences with others.
true minerals normally form by inorganic processes, some
organisms make them as shells or other parts of their bodies.
These so-called biominerals are of obvious organic origin
(made by plants and animals). Examples include aragonite
mineral crystals in clam shells and tiny magnetite crystals
in the human brain. People make cultured mineral crystals
in laboratories. Their chemical and physical properties are
identical to naturally-formed mineral crystals, but they are
not true minerals because they are synthetic (man-made,
not natural).
How Are Minerals Classified?
Geologists have identified and named thousands of different
kinds of minerals, but they are often classified into smaller
groups according to their importance, use, or chemistry.
For example, a group of only about twenty are known as
rock-forming minerals, because they are the minerals that
make up most of Earth’s crust. Another group is called the
industrial minerals, because they are the main non-fuel
raw materials used to sustain industrialized societies like
ours. Some industrial minerals are used in their raw form,
such as quartz (quartz sand), muscovite (used in computer
chips), and gemstones. Most are refined to obtain specific
elements such as iron, copper, and sulfur. All minerals are
also classified into the following chemical classes:
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Minerals and Rocks
Many people think of minerals as the beautiful natural
crystals mined from the rocky body of Earth and displayed
in museums or mounted in jewelry. But table salt, graphite
in pencil leads, and gold nuggets are also minerals.
What Are Minerals?
According to geologists, minerals are inorganic, naturally
occurring solids that have a definite chemical composition,
distinctive physical properties, and crystalline structure. In
other words, each mineral
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occurs in the solid, rocky body of Earth, where it formed
by processes that are inorganic (not involving life).
has a definite chemical composition of one or more
chemical elements that can be represented as a chemical formula (like NaCl for halite, FeS2 for pyrite, and
Au for pure “native gold”).
has physical properties (like hardness, how it breaks,
and color) that can be used to identify it.
has crystalline structure—an internal patterned
arrangement or geometric framework of atoms that can
be revealed by external crystal faces (FIGURES 3.1A, B),
the way a mineral breaks (FIGURE 3.2B), and in atomicresolution images (FIGURE 3.2C).
A few “minerals,” such as limonite (rust) and opal
(FIGURE 3.3) never form crystals, so they do not have
crystalline structure. They are mineral-like materials
(mineraloids) rather than true minerals. And even though all
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L A B O R AT O R Y 3
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Silicate minerals are composed of pure silicon dioxide
(SiO2, called quartz) or silicon-oxygen ions (SiO4)4combined with other elements. Examples are olivine:
(Fe, Mg)2SiO4, potassium feldspar: KAlSi3O8, and
kaolinite: Al2(Si4O10)(OH)8.
Oxide minerals contain oxygen (O2-) combined with
a metal (except for those containing silicon, which
are silicate minerals). Examples are hematite: Fe2O3,
magnetite: Fe2O3, and corundum: Al2O3.
Hydroxide minerals contain hydroxyl ions (OH)combined with other elements (except for those
containing silicon, which are silicate minerals).
Examples are goethite: FeO(OH) and limonite:
FeO(OH) # nH2O.
Sulfide minerals contain sulfur ions (S2-) combined
with metal(s) and no oxygen. Examples are pyrite:
FeS2, galena: PbS, and sphalerite: ZnS. When they are
scratched or crushed, one can usually smell the sulfur
in these minerals.
Sulfate minerals contain sulfate ions (SO4)2- combined with other elements. Examples include gypsum:
CaSO4 # H2O and barite: BaSO4.
Carbonate minerals contain carbonate ions
(CO3)2- combined with other elements. Examples
include calcite: CaCO3 and dolomite: CaMg(CO3)2.
These minerals react with acid, the way baking
soda (which is the mineral named nahcolite and the
chemical compound named sodium bicarbonate:
NaHCO3) reacts with acetic acid (CH3COOH) in
vinegar. Geologists use dilute hydrochloric acid (HCl)
to detect carbonate minerals because the reaction
makes larger bubbles. If a mineral reacts with the
dilute HCl, then it is a carbonate mineral.
Crystal
faces
6
1
2
5
4
3
Crystal
faces
A.
A rock made of two large, visible, quartz mineral crystals. Crystal
faces (flat outside surfaces) merge into three dimensional crystal
forms (geometric shapes). Crystal growth was unobstructed, except
where the two crystals touched and grew together (x1).
Top view: Crystal growth was unobstructed so
crystal faces are developed (x1).
x2
Side view:
Deformed
crystal faces
among
crowded
intergrown
crystals (x1).
B.
Rock made of many quartz mineral crystals. Note
how crystal growth was obstructed as the sides of
many crystals grew together (side view), but tips of
the crystals (top view) grew unobstructed into
six-sided pyramids. Iron impurity gives the purple
amethyst variety of quartz its color.
C.
Crystal growth of the
calcite mineral crystals
in this rock (marble)
was obstructed in
every direction. The
crystals grew together
as a dense mass of
odd-shaped crystals
instead of perfect
crystal forms.
Intergrown
crystals outlined
in black
Thin section (x30). The layers of
agate are made of long intergrown
quartz mineral crystals.
D.
Slice of rock (agate) cut with a diamond saw and polished. The layers are made of quartz mineral crystals that are
cryptocrystalline (not visible in hand sample). They can only be seen in a thin section (thin transparent slice of the
rock mounted on a glass slide) magnified with a microscope to 30 times larger than their actual size (x30).
FIGURE 3.1 Minerals and rocks. Most rocks are made of one or more mineral crystals.
Mineral Properties, Identification, and Uses
■
75
C. Scanning tunneling microscope (STM) image of galena showing
the orderly arrangement of its lead and sulfur atoms. Each sulfur
atom is bonded to four lead atoms in the image, plus a lead atom
beneath it. Similarly, each lead atom is bonded to four sulfur atoms
in the image, plus a sulfur atom beneath it.
B. When struck with a hammer, galena breaks along flat
cleavage surfaces (planes of weak chemical bonding within
the crystal) that have a silvery color, like metal, and intersect
at 90° angles to form shapes made of cubes.
x1
A. Galena mineral crystals form
cubic shapes that tarnish to a
dull gray color.
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Blue = S (sulfur) atoms, Orange = Pb (lead) atoms
nm = nanometer = 1 millionth of a millimeter
FIGURE 3.2 Crystal shape, cleavage, and atomic structure. Galena is lead
sulfide—PbS. It is an ore mineral from which lead (Pb) and sulfur (S) are extracted.
(STM image by C.M. Eggleston, University of Wyoming)
Halide minerals contain a halogen ion (F-, Cl-, Br-,
or I-) combined with a metal. Examples are halite:
NaCl and fluorite: CaF2.
Phosphate minerals contain phosphate ions (PO4)3combined with other elements. An example is apatite:
Ca5F(PO4)3(OH, F, Cl).
Native elements are elements in pure form, not combined with different elements. Examples include graphite: C, copper: Cu, sulfur: S2, gold: Au, and silver: Ag.
Opal is a residue of hydrated silicon dioxide that forms
light-colored translucent masses like this. Notice its lack
of crystals and cleavage. This “precious” opal has been
polished to enhance its internal flashes of color.
How Are Minerals Related to Rocks?
Most rocks are aggregates of one or more mineral crystals. For example, mineral crystals comprise all of the
rocks in FIGURE 3.1. Notice that you can easily detect
the mineral crystals in FIGURES 3.1A and 3.1B by their
flat faces, which are an external feature of the internal
geometric framework of their atoms. However, the crystals in many rocks have grown together in such a crowded
way that few faces are visible (FIGURES 3.1C). Some rocks
are also cryptocrystalline, made of crystals that are only
visible under a microscope (FIGURE 3.1D).
Earth is sometimes called the “third rock” (rocky
planet) from the Sun, because it is mostly made of rocks.
But rocks are generally made of one or more minerals,
which are the natural materials from which every inorganic
item in our industrialized society has been manufactured.
Therefore, minerals are the physical foundation of both
our rocky planet and our human societies.
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L A B O R AT O R Y 3
Limonite forms dull powdery yellow-brown to dense
dark brown masses like this. Notice its lack of crystals
and cleavage. It is a residue of hydrated iron oxide and/or
hydrated iron oxyhydroxide that you know as rust.
FIGURE 3.3 Mineraloids. Opal and limonite are naturallyoccurring inorganic materials, but they are amorphous (noncrystalline; they never form crystals). This makes them mineraloids
(amorphous mineral-like materials), rather true minerals, but they
are described, identified, and listed as minerals.
ACTIVITY
3.2 Mineral Properties
THINK
About It
|
How and why do people study
minerals?
OBJECTIVE Analyze and describe the physical and
chemical properties of minerals.
PROCEDURES
1. Before you begin, read the following background
information. This is what you will need:
____ Activity 3.2 Worksheets (pp. 102–103) and
pencil
____ set of mineral samples (obtained as directed
by your instructor)
____ set of mineral analysis tools (obtained as
directed by your instructor)
____ cleavage goniometer cut from GeoTools
Sheet 1 at the back of the manual
2. Then follow your instructor’s directions for
completing the worksheets.
What Are a Mineral’s Chemical and
Physical Properties?
The chemical properties of a mineral are its characteristics
that can only be observed and measured when or after it
undergoes a chemical change due to reaction with another
material. This includes things like if or how it tarnishes
(reacts with air or water) and whether or not it reacts with
acid. For example, calcite and other carbonate (CO3containing) minerals react with acid, and native copper
tarnishes to a dull brown or green color when it reacts with
air or water.
The physical properties of a mineral are its characteristics that can be observed (and sometimes measured) without
changing its composition. This includes things like how it
looks (color, luster, clarity) before it tarnishes or weathers
by reacting with air or water, how well it resists scratching
(hardness), how it breaks or deforms under stress (cleavage,
fracture, tenacity), and the shapes of its crystals. For example,
quartz crystals are hard to scratch, glassy, and transparent,
while talc is easily scratched, opaque, and feels greasy.
In this activity, you will use the properties of color and
clarity (before and after tarnishing), crystal form, luster
(before and after tarnishing), streak, hardness, cleavage, and
fracture to describe mineral samples. Additional properties—
such as tenacity, reaction with acid, magnetic attraction,
specific gravity, striations, and exsolution lamellae—can also
be helpful in analyzing particular minerals.
Color and Clarity. A mineral’s color is usually its most
noticeable property and may be a clue to its identity.
Minerals normally have a typical color, like gold. A rock
made up of one color of mineral crystals is usually made
up of one kind of mineral, and a rock made of more
than one color of mineral crystals is usually made up
of more than one kind of mineral. However, there are
exceptions, like the agate in FIGURE 3.1D. It has many
colors, but they are simply varieties (var.)—different
colors—of the mineral quartz. This means that a mineral cannot be identified solely on the basis of its color.
The mineral’s other properties must also be observed,
recorded, and used collectively to identify it. Most
minerals also tend to exhibit one color on freshly broken
surfaces and a different color on tarnished or weathered
surfaces. Be sure to note this difference, if present, to aid
your identification.
Mineral crystals may vary in their clarity: degree
of transparency or their ability to transmit light. They
may be transparent (clear and see-through, like window
glass), translucent (foggy, like looking through a steamedup shower door), or opaque (impervious to light, like
concrete and metals). It is good practice to record not
only a mineral’s color, but also its clarity. For example,
the crystals in FIGURE 3.1B are purple in color and have
transparent to translucent clarity. Galena mineral crystals
(FIGURE 3.2) are opaque.
Crystal Forms and Mineral Habits. The geometric shape
of a crystal is its crystal form. Each form is bounded by
flat crystal faces that intersect at specific angles and in
symmetrical relationships (FIGURE 3.1A and B). The crystal
faces are the outward reflection of the way that atoms or
groups of atoms bonded together in a three-dimensional
pattern as the crystal grew under specific environmental conditions. There are many named crystal forms
(FIGURE 3.4). Combinations of two or more crystals can
also form named patterns, shapes, or twins (botryoidal,
dendritic, radial, fibrous: FIGURE 3.4). A mass of mineral
crystals lacking a distinctive pattern of crystal growth is
called massive.
Development of Crystal Faces. The terms euhedral,
subhedral, and anhedral describe the extent to which a
crystal’s faces and form are developed. Euhedral crystals
have well developed crystal faces and clearly defined
and recognizable crystal forms (FIGURE 3.1A). They
develop only if a mineral crystal is unrestricted as it
grows. This is rare. It is more common for mineral
crystals to crowd together as they grow, resulting in a
massive network of intergrown crystals with deformed
crystal faces and odd shapes or imperfect crystal forms
(FIGURE 3.1B). Subhedral crystals are imperfect but have
enough crystal faces that their forms are recognizable.
Euhedral crystals have no crystal faces, so they have no
recognizable crystal form (FIGURE 3.1C). Most of the
laboratory samples of minerals that you will analyze do
not exhibit their crystal forms because they are small
broken pieces of larger crystals. But whenever the form
or system of crystals in a mineral sample can be detected,
then it should be noted and used as evidence for mineral
identification.
Mineral Properties, Identification, and Uses
■
77
Tetrahedron
(4 faces)
Needles
(acicular)
Twinned
Pyramidal
EQUANT
Cube
(6 faces)
Bladed
Dodecahedron
(12 faces)
Octahedron
((dipyramid))
Pyritohedron
(12 faces)
Dendritic
Tabular (shaped
like a book)
Fibrous
Radiating needles
Rhombohedron
(a leaning block with
6 faces, each a rhombus)
Prismatic
Wires
Scalenohedrons
Dipyramid prism
Botryoidal (bubbly
masses; radiating
needles inside)
FIGURE 3.4 Crystal forms and combinations. Crystal form is the geometric shape of a crystal, and is formed by intersecting flat outer
surfaces called crystal faces. Combinations of two or more crystals can form patterns, shapes, or twins that also have names. Massive refers to a
combination of mineral crystals so tightly inter-grown that their crystal forms cannot be seen in hand sample.
Crystal Systems. Each specific crystal form can be
classified into one of six crystal systems (FIGURE 3.5)
according to the number, lengths, and angular relationships of imaginary geometric axes along which its crystal
faces grew. The crystal systems comprise 32 classes of
crystal forms, but only the common crystal forms are
illustrated in FIGURE 3.5.
Mineral Habit. A mineral’s habit is the characteristic
crystal form(s) or combinations (clusters, coatings,
twinned pairs) that it habitually makes under a given set
of environmental conditions. Pyrite forms under a variety
of environmental conditions so it has more than one
habit. Its habit is cubes, pyritohedrons, octahedrons, or
massive (FIGURE 3.4).
Luster. A mineral’s luster is a description of how light
reflects light from its surfaces. Luster is of two main types—
metallic and nonmetallic—that vary in intensity from bright
(very reflective, shiny, polished) to dull (not very reflective,
not very shiny, not polished). For example, if you make a list
of objects in your home that are made of metal (e.g., coins,
knives, keys, jewelry, door hinges, aluminum foil), then
you are already familiar with metallic luster. Yet the metallic
objects can vary from bright (very reflective—like polished
jewelry, the polished side of aluminum foil, or new coins) to
dull (non-reflective—like unpolished jewelry or the unpolished side of aluminum foil).
78
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L A B O R AT O R Y 3
Metallic Luster. Minerals with a metallic luster (M)
reflect light just like the metal objects in your home—they
have opaque, reflective surfaces with a silvery, gold, brassy,
or coppery sheen (FIGURES 3.2B, 3.6A, 3.7A).
Nonmetallic Luster. All other minerals have a nonmetallic
luster (NM)—a luster unlike that of the metal objects in
your home (FIGURES 3.1, 3.2A, 3.3). The luster of nonmetallic minerals can also be described with the more
specific terms below:
■
Vitreous—very reflective luster resembling freshly
broken glass or a glossy photograph
■
Waxy—resembling the luster of a candle
■
Pearly—resembling the luster of a pearl
■
Earthy (dull)—lacking reflection, like dry soil
■
Greasy—resembling the luster of grease, oily
Tarnish and Submetallic Luster. Most metallic minerals will normally tarnish (chemically weather) to a
more dull nonmetallic luster, like copper coins. Notice
how the exposed metallic copper crystals in FIGURE 3.6
and the galena crystals in FIGURE 3.2A have tarnished
to a nonmetallic luster. Always observe freshly broken
surfaces of a mineral (e.g., FIGURE 3.2B) to determine
whether it has a metallic or nonmetallic luster. It is also
useful to note a mineral’s luster on fresh versus tarnished
Crystal Forms (Specific Geometric Shapes) and Their Classification into Six Systems
Cube
Octahedron
(8 equilateral triangles)
Rhombic dodecahedron
(12 faces)
Pyritohedron
(12 faces)
Equilateral
tetrahedron
Isometric (Cubic): Cubes and equidimensional shapes. Three axes intersect at 90° and are isometric (same in length).
Tetragonal dipyramid
(square cross section)
Tetragonal dipyramid prisms
(square cross section)
Isosceles tetrahedrons
(4 or 8 faces)
Tetragonal: Like isometric but longer in one direction. Three axes intersect at 90° but only two are equal in length.
Top
Side
Orthorhombic dipyramid
(tetragonal bipyramid)
Orthorhombic dipyramid prisms and tabular prisms
4- or 8-sided rectangular, squarish, or rhombic
(diamond-shaped) horizontal cross sections
Orthorhombic: Prisms and dipyramids with rhombic or rectangular cross sections. Three axes intersect at 90° but have different lengths.
Scalenohedron
(12 faces)
Hexagonal prisms
3-sided prism
Hexagonal
dipyramid prism
Rhombohedron
3-, 6-, or 12-sided
horizontal cross
sections, except for
rhombohedrons (6 faces)
Hexagonal: Rhombohedrons and mostly 3-, 6-, or 12-sided prisms and pyramids–three axes of equal length in one
plane and perpendicular to a fourth axis of different length.
Cross sections
Monoclinic prisms
Monoclinic tablet
Monoclinic blade
Monoclinic: Tablets (two very large faces like a book), prisms, and blades with six sides in diamond or parallelogram-shaped
cross section.Three axes of unequal length, two in one plane and perpendicular to a third axis.
Triclinic prisms and blades
Triclinic: Tabular shapes, often not symmetrical from one side to the other. Three axes of different lengths and all inclined
at each other (none are perpendicular to others).
FIGURE 3.5 Crystal systems. Each specific crystal form can be classified into one of six crystal systems (major groups) according to the
number, lengths, and angular relationships of imaginary geometric axes along which its crystal faces grew (red lines in the right-hand models
of each system above). Only the common crystal forms of each class are illustrated and named above.
Mineral Properties, Identification, and Uses
■
79
C
B
A
FIGURE 3.6 Native elements. The native elements are
minerals composed of just one element, like gold nuggets.
A. When freshly formed or broken, native copper (Cu, naturallyoccurring pure copper) has a reflective metallic luster like this
freshly-minted copper coin. However, these dendritic clusters of
native copper crystals have tarnished to nonmetallic dull brown
(A) and/or green (B) colors.
surfaces when possible. If you think that a mineral’s
luster is submetallic, between metallic and nonmetallic,
then it should be treated as metallic for identification
purposes.
Streak. Streak is the color of a mineral or other sub-
stance after it has been ground to a fine powder (so fine
that you cannot see the grains of powder). The easiest
way to do this is simply by scratching the mineral back
and forth across a hard surface such as concrete, or a
square of unglazed porcelain (called a streak plate). The
color of the mineral’s fine powder is its streak. Note that
A: MINERAL
CRYSTAL
(CUBE)
the brassy mineral in FIGURE 3.7 has a dark gray streak,
but the reddish silver mineral has a red-brown streak. A
mineral’s streak is usually similar even among all of that
mineral’s varieties.
If you encounter a mineral that is harder than the
streak plate, it will scratch the streak plate and make
a white streak of powder from the streak plate. The streak
of such hard minerals can be determined by crushing a
tiny piece of them with a hammer (if available). Otherwise,
record the streak as unknown.
Hardness (H). A mineral’s hardness is a measure of its
resistance to scratching. A harder substance will scratch
a softer one (FIGURE 3.8). German mineralogist Friedrich
Mohs (1773–1839) developed a quantitative scale of relative mineral hardness on which the softest mineral (talc)
has an arbitrary hardness of 1 and the hardest mineral
(diamond) has an arbitrary hardness of 10. Highernumbered minerals will scratch lower-numbered minerals
(e.g., diamond will scratch talc, but talc cannot scratch
diamond). Mohs Scale of Hardness (FIGURE 3.9) is widely
used by geologists and engineers. When identifying a
mineral, you should mainly be able to distinguish minerals that are relatively hard (6.0 or higher on Mohs Scale)
from minerals that are relatively soft (less than or equal to
5.5 on Mohs Scale). You can use common objects such as
a glass plate (FIGURE 3.9), pocket knife, or steel masonry
nail to make this distinction as follows.
■
Hard minerals: Will scratch glass; cannot be scratched
with a knife blade or masonry nail.
■
Soft minerals: Will not scratch glass; can be scratched
with a knife blade or masonry nail.
You can determine a mineral’s hardness number on
Mohs Scale by comparing the mineral to common objects
B: FRAGMENT
OF MINERAL
CRYSTAL
Streak
plate
Streak
plate
Color: brassy
Streak: dark gray
Luster: metallic (M)
Color: reddish silver
Streak: red-brown
Luster: metallic (M) to nonmetallic (NM)
FIGURE 3.7 Streak tests. Determine a mineral’s streak (color in powdered form) by scratching it across a streak plate with significant force,
then blowing away larger pieces of the mineral to reveal the color of the powder making the streak. If you do not have a streak plate, then
determine the streak color by crushing or scratching part of the sample to see the color of its powdered form.
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L A B O R AT O R Y 3
shown in FIGURE 3.9 or pieces of the minerals in Mohs Scale.
Commercial hardness kits contain a set of all of the minerals
in FIGURE 3.9 or a set of metal scribes of known hardnesses.
When using such kits to make hardness comparisons, remember that the harder mineral/object is the one that scratches,
and the softer mineral/object is the one that is scratched.
Hardness test
Glass
plate
FIGURE 3.8 Hardness test. You can test a mineral’s hardness
(resistance to scratching) using a glass plate, which has a hardness of
5.5 on Mohs Scale of Hardness (FIGURE 3.9). Be sure the edges of the
glass have been dulled. If not, then wrap the edges in masking tape
or duct tape. Hold the glass plate firmly against a flat table top, then
forcefully try to scratch the glass with the mineral sample. A mineral that
scratches the glass is a hard mineral (i.e., harder than 5.5). A mineral that
does not scratch the glass is a soft mineral (i.e., less than or equal to 5.5).
Mohs Scale
of
Hardness*
Cleavage and Fracture. Cleavage is the tendency of
some minerals to break (cleave) along flat, parallel surfaces
(cleavage planes) like the flat surfaces on broken pieces
of galena (FIGURE 3.2B). Cleavage planes are surfaces of
weak chemical bonding (attraction) between repeating,
parallel layers of atoms in a crystal. Each different set of
parallel cleavage planes is referred to as a cleavage direction.
Cleavage can be described as excellent, good, or poor
(FIGURE 3.10). An excellent cleavage direction reflects
light in one direction from a set of obvious, large, flat,
parallel surfaces. A good cleavage direction reflects light
in one direction from a set of many small, obvious, flat,
parallel surfaces. A poor cleavage direction reflects light
from a set of small, flat, parallel surfaces that are difficult
to detect. Some of the light is reflected in one direction
from the small cleavage surfaces, but most of the light
is scattered randomly by fracture surfaces separating the
cleavage surfaces.
Hardness of Some Common Objects
(Harder objects scratch softer objects)
10 Diamond
HARD
9 Corundum
8 Topaz
7 Quartz
6.5 Streak plate
6 Orthoclase Feldspar
5.5 Glass,
Masonry nail,
Knife blade
5 Apatite
4.5 Wire (iron) nail
SOFT
4 Fluorite
3 Calcite
3.5 Brass (wood screw, washer)
2.9 Copper coin (penny)
2.5 Fingernail
2 Gypsum
1 Talc
* A scale for measuring relative mineral hardness (resistance to scratching).
FIGURE 3.9 Mohs Scale of Hardness (resistance to scratching). Hard minerals have a Mohs hardness number greater than 5.5, so they
scratch glass and cannot be scratched with a knife blade or masonry (steel) nail. Soft minerals have a Mohs hardness number of 5.5 or less, so
they do not scratch glass and are easily scratched by a knife blade or masonry (steel) nail. A mineral’s hardness number can be determined by
comparing it to the hardness of other common objects or minerals of Mohs Scale of Hardness.
Mineral Properties, Identification, and Uses
■
81
Light rays
A. Cleavage excellent or perfect (large, parallel, flat surfaces)
Light rays
Cleavage Direction. Cleavage planes are parallel surfaces
of weak chemical bonding (attraction) between repeating
parallel layers of atoms in a crystal, and more than one set
of cleavage planes can be present in a crystal. Each different
set has an orientation relative to the crystalline structure
and is referred to as a cleavage direction (FIGURE 3.12). For
example, muscovite (FIGURE 3.13) has one excellent cleavage direction and splits apart like pages of a book (book
cleavage). Galena (FIGURE 3.2) breaks into small cubes and
shapes made of cubes, so it has three cleavage directions
developed at right angles to one another. This is called
cubic cleavage (FIGURE 3.12).
Cleavage Direction in Pyriboles. Minerals of the
pyroxene (e.g., augite) and amphibole (e.g., hornblende)
groups generally are both dark-colored (dark green to
black), opaque, nonmetallic minerals that have two good
B. Cleavage good or imperfect (small, parallel, flat,
stair-like surfaces)
Light rays
A: Pure quartz (var. rock crystal) is colorless,
transparent, nonmetalic, and has conchoidal
fracture (like glass).
C. Cleavage poor (a few small, flat surfaces difficult to detect)
Light rays
Conchoidal:
smooth
curved
fracture
surfaces,
like glass
Uneven:
rough
irregular
fracture
surfaces
Hackly:
breaks
along
jagged
surfaces
like broken
metal
Splintery:
splinters
like wood
Fibrous:
separates
into soft
fibers, like
cloth
D. Fractures (broken surfaces lacking cleavage planes)
FIGURE 3.10 Recognizing cleavage and fracture. Illustrated
cross sections of mineral samples to show degrees of development
of cleavage—the tendency for a mineral to break along one or
more sets of parallel, planar, reflective surfaces called cleavage
planes. If a broken piece of a mineral crystal is rotated in bright light,
its cleavage planes will be revealed by periodic flashes of light from
one large, or many small, flat parallel surfaces. If no such reflective
flashes of light occur, then the mineral sample has no cleavage.
Fracture refers to any break in a mineral that does not occur along
a cleavage plane. Therefore, fracture surfaces are normally not flat
and they never occur in parallel sets.
Fracture refers to any break in a mineral that does not
occur along a cleavage plane. Therefore, fracture surfaces
are normally not flat and they never occur in parallel sets.
Fracture can be described as uneven (rough and irregular,
like the milky quartz in FIGURE 3.11B), splintery (like splintered wood), or hackly (having jagged edges, like broken
metal). Pure quartz (FIGURE 3.11A) and mineraloids like
opal (FIGURE 3.3) tend to fracture like glass—along ribbed,
smoothly curved surfaces called conchoidal fractures.
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L A B O R AT O R Y 3
(x1)
(x1)
B: Milky quartz forms when the quartz has
microscopc fluid inclusions, usually water. It has
an irregular (rough, uneven) fracture.
FIGURE 3.11 Fracture in quartz—SiO2 (silicon dioxide).
These hand samples are broken pieces of quartz mineral crystals so
no crystal faces are present. Note the absence of cleavage and the
presence of conchoidal (like glass) to uneven fracture.
Number of Cleavages
and Their Directions
Name and Description
of How the Mineral Breaks
No cleavage
(fractures only)
No parallel broken surfaces;
may have conchoidal
fracture (like glass)
Shape of Broken Pieces
(cleavage directions
are numbered)
Illustration of
Cleavage Directions
None
(no cleavage)
Quartz
Basal (book) cleavage
1 cleavage
“Books” that split apart
along flat sheets
Prismatic cleavage
2 cleavages
intersect
at or near 90°
1
Muscovite, biotite, chlorite (micas)
Orthoclase 90°
(K-spar)
1
2
Elongated forms that fracture
along short rectangular
cross sections
Plagioclase 86° & 94°,
pyroxene (augite) 87° & 93°
2 cleavages
do not intersect
at 90°
Prismatic cleavage
1
2
Elongated forms that fracture
along short parallelogram
cross sections
Amphibole (hornblende) 56° & 124°
1
3 cleavages
intersect
at 90°
Cubic cleavage
2
3
Shapes made of cubes and
parts of cubes
Halite, galena
3 cleavages
do not intersect
at 90°
1
Rhombohedral cleavage
3
2
Shapes made of
rhombohedrons and parts
of rhombohedrons
Calcite and dolomite 75° & 105°
4 main cleavages
intersect at 71° and 109°
to form octahedrons,
which split along hexagonshaped surfaces; may
have secondary
cleavages at 60° and 120°
6 cleavages
intersect at
60° and 120°
Octahedral cleavage
4
Shapes made of
octahedrons and parts
of octahedrons
3
1
2
Fluorite
2
Dodecahedral cleavage
Shapes made of
dodecahedrons and parts
of dodecahedrons
1
3
5
4
6
Sphalerite
FIGURE 3.12 Cleavage in minerals.
Mineral Properties, Identification, and Uses
■
83
Cleavage
surface
Notice how this muscovite mica splits
apart into thin, transparent, flexible sheets
along its excellent cleavage surfaces
Cleavage
surface
Fracture
surface
Cleavage
surface
87°
Crystal
Cleavage
surface
FIGURE 3.13 Cleavage in mica. Mica is a group of silicate
minerals that form very reflective (vitreous) tabular crystals with
one excellent cleavage direction. The crystals split easily into
thin sheets, like pages of a book. This is called book cleavage.
Muscovite mica is usually silvery brown in color. Biotite mica is
always black.
Crystal
fragment
A: Pyroxenes (like augite) have two prominent
cleavage directions that intersect at nearly right
angles (87° and 93°). They form prismatic crystals
with a squarish cross section. The crystals break
into blocky fragments.
Cleavage
surface
cleavage directions. The two groups of minerals are sometimes difficult to distinguish, so some people identify
them collectively as pyriboles. However, pyroxenes can be
distinguished from amphiboles on the basis of their cleavage. The two cleavages of pyroxenes intersect at 87° and
93°, nearly at right angles (FIGURE 3.14A). The two cleavages of amphiboles intersect at angles of 56° and 124°
(FIGURE 3.14B). These angles can be measured in hand
samples using the cleavage goniometer from GeoTools
Sheet 1 at the back of this manual. Notice how a green
cleavage goniometer was used to measure angles between
cleavage directions in FIGURE 3.14.
Cleavage Direction in Feldspars. Feldspars have two
excellent to good cleavage directions, plus uneven fracture
(FIGURE 3.15). The cleavage goniometer from GeoTools
Sheet 1 can be used to distinguish potassium feldspar
(orthoclase) from plagioclase (FIGURE 3.15).
Other Properties. There are additional mineral proper-
ties, too numerous to review here. However, the following other properties are typical of specific minerals or
mineral groups:
Tenacity is the manner in which a substance resists
breakage. Terms used to describe mineral tenacity include
brittle (shatters like glass), malleable (like modeling clay
or gold; can be hammered or bent permanently into new
shapes), elastic or flexible (like a plastic comb; bends but
returns to its original shape), and sectile (can be carved
with a knife).
Reaction to acid differs among minerals. Cool, dilute
hydrochloric acid (1–3% HCl) applied from a dropper bottle is a common “acid test.” All of the so-called
carbonate minerals (minerals with a chemical composition
84
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L A B O R AT O R Y 3
Cleavage
surface
Crystal
Crystal
fragment
Fracture
surface
56°
B: Amphiboles (like hornblende) have two prominent
cleavage directions that intersect at 56° and 124°.
They form more blade-like crystals with a
six-sided diamond-shaped cross section and
break into blade-like fragments.
FIGURE 3.14 Cleavage in pyroxenes and amphiboles.
Pyroxenes and amphiboles are two groups of dark colored silicate
minerals with many similar properties. The main feature that
distinguishes them is their cleavage.
including carbonate, CO3) will effervesce (“fizz”) when a
drop of such dilute HCl is applied to one of their freshly
exposed surfaces (FIGURE 3.16). Calcite 1CaCO32 is the
most commonly encountered carbonate mineral and
effervesces in the acid test. Dolomite 3Ca,Mg1CO3224 is
Plagioclase
Pink K-feldspar (orthoclase)
Fracture
surfaces
86°
90°
Right-angle
cleavage
Cleavage
planes
with no
striations
A. Plagioclase
Cleavage
plane with
parallel,
closely spaced
striations
Fracture
surfaces at
broken ends
of crystals
Cleavage plane
with subparallel
color variation
bands from
exsolution
lamellae
Cleavage
plane with
parallel,
closely spaced
striations
94°
White K-feldspar (orthoclase)
90°
Right-angle
cleavage
B. Pink K-feldspar (orthoclase)
Cleavage surface
with striations
C. Rock comprised of plagioclase crystals
FIGURE 3.15 Common feldspars. Note how the cleavage goniometer can be used to distinguish potassium feldspar (K-spar, orthoclase)
from plagioclase. The K-spar or orthoclase (Greek, ortho—right angle and clase—break) has perfect right-angle (90º) cleavage. Plagioclase
(Greek, plagio—oblique angle and clase—break) does not. A. Plagioclase often exhibits hairline striations on some of its cleavage surfaces.
They are caused by twinning: microscopic intergrowths between symmetrically-paired microcrystalline portions of the larger crystal. B. K-par
(orthoclase) crystals may have intergrowths of thin, discontinuous, exsolution lamellae. They are actually microscopic layers of plagioclase that
form as the K-spar cools, like fat separates from soup when it is refrigerated. C. Hand sample of a rock that is an aggregate of intergrown plagioclase mineral crystals. Individual mineral crystals are discernible within the rock, particularly the cleavage surfaces that have characteristic
hairline striations.
another carbonate mineral that resembles calcite, but it
will fizz in dilute HCl only if the mineral is first powdered.
(It can be powdered for this test by simply scratching the
mineral’s surface with the tip of a rock pick, pocket knife,
or nail.) If HCl is not available, then undiluted vinegar can
be used for the acid test. It contains acetic acid (but the
effervescence will be much less violent).
Striations are straight “hairline” grooves on the
cleavage surfaces or crystal faces of some minerals. This
can be helpful in mineral identification. For example,
you can use the striations of plagioclase feldspar
(FIGURE 3.15A) to distinguish it from potassium feldspar
(K-feldspar, FIGURE 3.15B). Plagioclase feldspar has faint
hairline striations on surfaces of one of its two cleavage
directions. In contrast, K- feldspar (orthoclase) sometimes
has internal exsolution lamellae, which are faint streaks of
plagioclase that grew inside of it.
Magnetism influences some minerals, such as magnetite. The test is simple: check to see if the mineral is
attracted to a magnet. Lodestone is a variety of magnetite
that is itself a natural magnet. It will attract steel paperclips. Some other minerals may also be weakly attracted to
a magnet (e.g., hematite, bornite, and pyrrhotite).
Specific Gravity (SG). Density is a measure of an object’s
mass (weighed in grams, g) divided by its volume (in
cubic centimeters, cm3). Specific gravity is the ratio of the
density of a substance divided by the density of water. Since
water has a density of 1 g>cm3 and the units cancel out,
specific gravity is the same number as density but without
any units. For example, the mineral quartz has a density of
2.65 g>cm3 so its specific gravity is 2.65 (i.e., SG = 2.65).
Hefting is an easy way to judge the specific gravity of one
mineral relative to another. This is done by holding a piece
of the first mineral in one hand and holding an equal-sized
piece of the second mineral in your other hand. Feel the
difference in weight between the two samples (i.e., heft the
samples). The sample that feels heavier has a higher specific
gravity than the other. Most metallic minerals have higher
specific gravities than nonmetallic minerals.
Mineral Properties, Identification, and Uses
■
85
Why Are Density and Specific Gravity
Important?
x1
FIGURE 3.16 Acid test. Place a drop of weak hydrochloric acid
(HCl) on the sample. If it effervesces (reacts, bubbles), then it is a
carbonate (CO3- containing) mineral. Please wipe the sample dry
with a paper towel after doing this test! Note that the mineral in this
example occurs in several different colors and can be scratched by a
wire (iron) nail. The yellow sample is a crystal of this mineral, but the
other samples are broken pieces of crystals that reveal the mineral’s
characteristic cleavage angles.
ACTIVITY
3.3 Determining Specific
Gravity (SG)
THINK
How and why do people study
About It minerals?
OBJECTIVE Measure the volume and mass of
minerals, calculate their specific gravities, and use the
results to identify them.
PROCEDURES
1. Before you begin, read the following background
information. Your instructor will provide
laboratory equipment, but this is what you will
need to bring to lab:
___ Activity 3.3 Worksheet (p. 104) and pencil
___ calculator
2. Then follow your instructor’s directions about
where to obtain laboratory equipment and
mineral samples, how to work safely, and how to
complete the worksheet.
86
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L A B O R AT O R Y 3
Have you ever considered buying silver coins as an
investment? If so, then you should be wary of deceptive sales. For example, there have been reports of less
valuable silver-plated copper coins marketed as pure
silver coins. Copper has a specific gravity of 8.94,
which is very close to silver’s specific gravity of 9.32.
So, even experienced buyers cannot tell a solid silver
coin from a silver-plated copper coin just by hefting it
to approximate its specific gravity. They must determine the coin’s exact specific gravity as one method
of ensuring its authenticity. Mineral identification is
also aided by knowledge of specific gravity. If you heft
same-sized pieces of the minerals galena (lead sulfide,
an ore of lead) and quartz, you can easily tell that one
has a much higher specific gravity than the other. But
the difference in specific gravities of different minerals is
not always so obvious. In this activity you will learn how
to measure the volume and mass of mineral samples,
calculate their specific gravities, and use the results to
identify them.
Before you begin, read the following background
information and be sure you have a pencil, eraser, and
Worksheet 3.3 (p. 102). Then complete the activity and
Worksheet 3.3.
How to Determine Volume. Recall that volume is the
amount of space that an object takes up. Most mineral
samples have odd shapes, so their volumes cannot be
calculated from linear measurements. Their volumes
must be determined by measuring the volume of water
they displace. This is done in the laboratory with a
graduated cylinder (FIGURE 3.17), an instrument used to
measure volumes of fluid (fluid volume). Most graduated
cylinders are graduated in metric units called milliliters
(mL or ml), which are thousandths of a liter. You should
also note that 1 mL (1 ml) of fluid volume is exactly the
same as 1 cm3 of linear volume.
Procedures for determining the volume of a
mineral sample are provided in FIGURE 3.17. Note
that when you pour water into a glass graduated
cylinder, the surface of the liquid is usually a curved
meniscus, and the volume is read at the bottom of its
concave surface. In most plastic graduated cylinders,
however, there is no meniscus. The water level is flat
and easy to read.
If you slide a mineral sample into a graduated cylinder
full of water (so no water splashes out), then it takes up
space previously occupied by water at the bottom of the
graduated cylinder. This displaced water has nowhere to
go except higher into the graduated cylinder. Therefore,
the volume of the mineral sample is exactly the same as the
volume of fluid (water) that it displaces.
How to Determine Mass. Earth materials do not just take
up space (volume). They also have a mass of atoms that
can be weighed. You will use a gram balance to measure
the mass of materials (by determining their weight under
the pull of Earth’s gravity). The gram (g) is the basic unit
of mass in the metric system, but instruments used to
measure grams vary from triple-beam balances to spring
scales to digital balances (page viii). Consult with your
laboratory instructor or other students to be sure that you
understand how to read the gram balance provided in
your laboratory.
WATER DISPLACEMENT METHOD
FOR DETERMINING VOLUME
OF A MINERAL SAMPLE
mL
10
Written mL or ml
mL
10
9
9
8
8
7
7
6
5
C. Volume
of water is
2.8 mL
5.0 mL
6
5
4
3
7.8 mL
4
Mineral
sample
3
2
2
1
1
How to Calculate Density and Specific Gravity. Every
material has a mass that can be weighed and a volume of
space that it occupies. However, the relationship between
a material’s mass and volume tends to vary from one
kind of material to another. For example, a bucket of
rocks has much greater mass than an equal-sized bucket
of air. Therefore a useful way to describe an object is to
determine its mass per unit of volume, called density.
Per refers to division, as in miles per hour (distance
divided by time). So density is the measure of an object’s
mass divided by its volume (density = mass ÷ volume).
Scientists and mathematicians use the Greek character
rho (r) to represent density. Also, the gram (g) is the
basic metric unit of mass, and the cubic centimeter is
the basic unit of metric volume (cm3), so density (r) is
usually expressed in grams per cubic centimeter (g/cm3).
For example:
Mineral sample weighs 44.0 grams
Mineral sample takes up 11.0 ml of volume
A. Starting volume
of water
B. Ending volume
of water
=
PROCEDURES
A. Place water in the bottom of a graduated
cylinder. Add enough water to be able to totally
immerse the mineral sample. It is also helpful to
use a dropper bottle or wash bottle and bring
the volume of water (before adding the mineral
sample) up to an exact graduation mark like the
5.0 mL mark above. Record this starting volume
of water.
44.0 g
11.0 cm3
= 4.00 g>cm3 = r
Specific gravity (SG) is the ratio of the density
of a substance divided by the density of water. Since
water has a density of 1 g>cm3 and the units cancel out,
specific gravity is the same number as density but without
any units. In the example above, the specific gravity of
the mineral sample would be 4.00 (i.e., SG = 4.00).
The mineral quartz has a density of 2.65 g/cm3 so its
specific gravity is 2.65 (i.e., SG = 2.65).
B. Carefully slide the mineral sample down into
the same graduated cylinder, and record the
ending volume of the water (7.8 mL in the above
example).
C. Subtract the starting volume of water from
the ending volume of water to obtain the
displaced volume of water. In the above
example: 7.8 mL – 5.0 mL = 2.8 mL (2.8 mL is
the same as 2.8 cm3 ). This volume of displaced
water is the volume of the mineral sample.
FIGURE 3.17 How to determine volume of a mineral sample.
Calculating Density and Specific Gravity—
The Math You Need
You can learn more about calculating density
and specific gravity at this site featuring
The Math You Need, When You Need It
math tutorials for students in introductory
geoscience courses: http://serc.carleton.edu/
mathyouneed/density/index.html
Mineral Properties, Identification, and Uses
■
87
ACTIVITY
3.4 Mineral Identification
and Uses
THINK
How and why do people study
About It minerals? How do you personally
depend on minerals and elements
extracted from them?
OBJECTIVE Identify common minerals on the basis of
their properties and assess how you depend on them.
PROCEDURES
1. Before you begin, read the introduction and
mineral identification procedures below. Your
instructor will provide laboratory equipment, but
this is what you will need to bring to lab:
___ Activity 3.4 Worksheets (pp. 105–108) and
pencil
2. To complete the activity, follow your instructor’s
directions about where to obtain a set of mineral
analysis tools and mineral samples and any
additional procedures for completing Worksheet 3.4
(which you will also need for Activity 3.5).
3. When you have completed your worksheets,
reflect on how you depend on each of the minerals
that you identified. What did you learn about how
you depend on minerals? Be prepared to discuss this
question and your mineral identifications. Save your
Activity 3.4 worksheets to complete Activity 3.5.
Introduction
You are expected to learn how to identify common
minerals on the basis of their properties and assess how
you depend on them. The ability to identify minerals is
one of the most fundamental skills of an Earth scientist.
It also is fundamental to identifying rocks, for you must
first identify the minerals comprising them. Only after
minerals and rocks have been identified can their origin,
classification, and alteration be adequately understood. Mineral identification is based on your ability to
describe mineral properties using identification charts
(FIGURES 3.18–3.20) and a Mineral Database (FIGURE
3.21). The database also lists the chemical composition
and some common uses for each mineral. Some minerals, like halite (table salt) and gemstones are used in their
natural state. Others are valuable as ores—materials from
which specific chemical elements (usually metals) can be
extracted at a profit.
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L A B O R AT O R Y 3
Mineral Identification Procedures
Obtain a set of mineral samples and analysis tools according to your instructor’s instructions. For each sample, fill
in the Activity 3.3 tear-out worksheet using the procedures
provided below.
1. Record the sample number or letter.
2. Determine and record the mineral’s luster as metallic
(M) or nonmetallic (NM)
A. Metallic (M): mineral is opaque, looks like metal
or sort of like metal)
B. Nonmetallic (NM): e.g., vitreous (glassy, glossy
reflection), waxy, pearly, earthy/dull, greasy
3. Determine and record the mineral’s hardness
(FIGS. 3.8, 3.9): give a hardness range, if possible.
4. Determine and record the mineral’s cleavage (if
present, FIGURES. 3.10–3.16) and fracture (if present,
FIGURE 3.10). For cleavage, determine number of
cleavage directions or name, if possible (FIGURE 3.12).
5. Determine and record the mineral’s color (fresh
surface) and streak (using a streak plate).
Minerals harder than 6.5 will scratch the streak
plate, so no streak can be determined for them.
6. Determine and record other notable properties
like these:
A. What is the mineral’s tenacity: brittle, elastic,
malleable, or sectile (can be carved with a knife)?
B. Does the mineral sample display magnetic
attraction (strongly or weakly)?
C. Does the mineral sample display a reaction with
acid (dilute HCl)?
D. If crystals are visible, then what is their crystal
form?
E. Does the mineral sample have striations on
cleavage surfaces or crystal faces or exsolution
lamellae (FIGURE 3.15)?
F. Estimate specific gravity (SG) as low,
intermediate, or high.
G. Does the mineral sample have any unique
diagnostic properties like smell when scratched or
during acid test?
7. Use mineral identification figures to identify the name
of the mineral.
A. If the mineral is opaque and metallic or
submetallic, follow steps 1–5 in FIGURE 3.18.
B. If the mineral is light colored and nonmetallic,
then follow steps 1–4 in FIGURE 3.19.
C. If the mineral is dark colored and nonmetallic,
then follow steps 1–4 in FIGURE 3.20.
8. Use the Mineral Database (FIGURE 3.21) and
FIGURE 3.22 to determine and record the mineral’s
chemical composition and help you determine
how you personally depend on the mineral
(including commodities refined from it). For more
information about specific minerals or elements, you
can refer to the U.S. Geological Survey’s Mineral
Commodity Summaries (http://minerals.usgs.gov/
minerals/pubs/mcs/).
ACTIVITY
3.5 The Mineral Dependency
Crisis
THINK
How do you personally depend on
About It minerals and elements extracted
from them? How sustainable is your
dependency on minerals and elements
extracted from them?
OBJECTIVE Evaluate your personal and U.S.
dependency on minerals.
PROCEDURES
1. Before you begin, read the background
information below and on page 99. Your instructor
will provide laboratory equipment, but this is
what you will need to bring to lab:
___ Activity 3.5 Worksheet (p. 109) and pencil
___ Activity 3.4 Worksheets that you already
completed
2. Then refer to FIGURE 3.22, and follow your
instructor’s directions about how to complete
the Activity 3.5 worksheet.
goggles, missile systems, and medical equipment. China
currently produces nearly all of the world’s supply of rare
earth elements, and the United States produces almost
none. This has created what is widely known as the “rare
earth crisis,” and a shortage of rare earth elements used to
make fluorescent light bulbs has become widely known
as the “phosphor crisis.” Yet the United States also relies
on foreign supplies of many other minerals and elements
extracted from them. Has the United States entered an
unsustainable level of mineral dependency?
U.S. Net Import Reliance on Non-fuel
Mineral Resources
Commodities are natural materials that people buy and
sell, because they are required to sustain our wants and
needs. Three classes are: agricultural products, energy
resources, and non-fuel mineral resources. The nonfuel mineral resources include rocks, minerals used in
their unrefined state or as ore from which specific elements can be profitably refined, and chemical elements
extracted from ores. The U.S. Geological Survey (USGS)
has determined that the United States was the world’s
largest user of non-fuel mineral resources in 2012 (about
12,000 pounds, or 11.3 metric tons, per person each
year). To sustain its needs, the U.S. imported some of the
minerals (and elements already extracted from them) that
it needed. FIGURE 3.22 shows the 2012 U.S. net import
reliance (expressed as a percent) on some selected minerals and elements refined from them. The United States
exports some of the same non-fuel mineral resources
that it imports, so net import reliance is the total of U.S.
production and imports, minus the percentage of exports.
A net import reliance of 80% means that 80% of the
resource is imported. FIGURE 3.22 does not include all of
the rare earth elements. Also not shown are minerals and
elements for which the U.S. is less than 5% import reliant (or a net exporter).
USGS Mineral Resources Data
System (MRDS)
Mineral Dependency
Did you know that some of the minerals used to make
your cell phone and fluorescent light bulbs are quite
rare nonrenewable resources? Many high-tech products
depend on such nonrenewable mineral resources, yet
many are either not mined within the United States
or are mined here only in small quantities. The locations where they can be economically extracted in the
United States have already been mined or are too small
to be developed. Of particular concern are minerals
mined as ores for rare earth elements, a group of 17 elements used in products like fluorescent light bulbs, flat
screen televisions, cell phones, computers, solar panels,
wind turbines, hybrid cars, cameras, DVDs, rechargeable batteries, magnets, medical equipment, night-vision
Recall that commodities are natural materials that people
buy and sell, because they are required to sustain our
wants and needs. Three classes are: agricultural products,
energy resources, and non-fuel mineral resources. The
U.S. Geological Survey (USGS) divides the non-fuel
mineral resources into two groups. Nonmetallic mineral
resources are mostly rocks made of unrefined minerals
(such as rock salt) and rocks (gravel, granite, marble).
Metallic mineral resources are ores (rocks or minerals
from which chemicals, usually metals, can be extracted
at a profit) and chemical elements that have already
been extracted from ore minerals. The USGS Mineral
Resources Data System (MRDS) is a global database
of both kinds of mineral resources and where they have
been found and/or processed.
Mineral Properties, Identification, and Uses
■
89
METALLIC AND SUBMETALLIC (M) MINERAL IDENTIFICATION
STEP 1:
What is the
mineral’s
hardness?
STEP 2:
Does the
mineral
have
cleavage?
HARD
(H > 5.5)
Scratches glass
STEP 3:
What is the
mineral’s
streak?
Pyrite
Silvery dark gray to black; Tarnishes gray or rusty
yellow-brown; Strongly attracted to a magnet and may
be magnetized; H 6–6.5; Crystals: octahedrons
Magnetite
Yellow-brown
Color submetallic silvery brown; Tarnishes to dull and
earthy yellow-brown to brown rust colors; H 1–5.5;
More commonly occurs in its nonmetallic yellow to
brown forms (H 1–5)
Limonite
Brown
Color silvery black to black; Tarnishes gray to black;
H 5.5–6; May be weakly attracted to a magnet;
Crystals: octahedrons
Chromite
Red to
red-brown
Color steel gray, reddish-silver, to glittery bright silver
(var. specular); Both metallic varieties have the
characteristic red-brown streak; May be attracted to a
magnet; H 5–6; Also occurs in nonmetallic, dull to
earthy, red to red-brown forms
Dark gray
to black
Color bright silvery gray; Tarnishes dull gray; Brittle:
breaks into cubes and shapes made of cubes; H 2.5;
Crystals: cubes or octahedrons; Feels heavy for its
size because of high specific gravity
Galena
White to pale
yellow-brown
Color silvery yellow-brown, silvery red, or black with
submetallic to resinous luster; Tarnishes brown or
black; H 3.5–4.0; smells like rotten eggs when
scratched, powdered, or in acid test
Sphalerite
Color bright silvery gold; Tarnishes bronze brown
brassy gold, or iridescent blue-green and red;
H 3.5–4.0; Brittle; uneven fracture; Crystals:
tetrahedrons
Chalcopyrite
Color characteristically brownish-bronze; Tarnishes
bright iridescent purple, blue, and/or red, giving It its
nickname “peacock ore”; May be weakly attracted to
a magnet; H 3; Usually massive, rare as cubes or
dodecahedrons
Bornite
Color opaque brassy to brown-bronze; Tarnishes dull
brown, may have faint iridescent colors; Fracture
uneven to conchoidal; No cleavage; Attracted to a
magnet; H 3.5–4.5; Usually massive or masses of tiny
crystals; Resembles chalcopyrite, which is softer and
not attracted to a magnet
Pyrrhotite
Color dark silvery gray to black; Can be scratched
with your fingernail; Easily rubs off on your fingers and
clothes, making them gray; H 1–2
Graphite
Yellow-brown
Metallic or silky submetallic luster, Color dark brown,
gray, or black; H 5–5.5; Forms layers of radiating
microscopic crystals and botryoidal masses
Goethite
Copper
Color copper; Tarnishes dull brown or green;
H 2.5–3.0; Malleable and sectile; Hackly fracture;
Usually forms dendritic masses or nuggets
Copper (native copper)
Gold
Color yellow gold; Does not tarnish; Malleable and
sectile; H 2.5–3.0; Forms odd-shaped masses,
nuggets, or dendritic forms
Gold (native gold)
Silvery white
Color silvery white to gray; Tarnishes gray to black;
H 2.5–3.0; Malleable and sectile; Forms dendritic
masses, nuggets, or curled wires
Silver (native silver)
Not scratched
by masonry nail
or knife blade
HARD
or
SOFT
Cleavage
good to
excellent
SOFT
(H < 5.5)
Dark gray
to black
Does not
scratch glass
Scratched by
masonry nail or
knife blade
STEP 5:
Mineral name. Find
out more about it in
the mineral
database (Fig.3.21).
Color silvery gold; Tarnishes brown; H 6–6.5; Brittle;
conchoidal to uneven fracture; Crystals: cubes (may be
striated), pyritohedrons, or octahedrons; Distinguished
from chalcopyrite, which is soft
Dark gray
to black
Cleavage
absent,
poor, or
not visible
STEP 4:
Match the mineral’s
physical properties to other
characteristic properties
below.
Cleavage
absent,
poor, or
not visible
Hematite
FIGURE 3.18 Identification chart for opaque minerals with metallic or submetallic luster (M) on freshly broken surfaces.
90
■
L A B O R AT O R Y 3
DARK TO MEDIUM-COLORED NONMETALLIC (NM) MINERAL IDENTIFICATION
STEP 1:
What is the
mineral’s
hardness?
STEP 2:
What is
the
mineral’s
cleavage?
STEP 4:
Find mineral name(s) and
check the mineral
database for additional
properties (Figure 3.21).
STEP 3:
Compare the mineral’s
physical properties to other
distinctive properties below.
Translucent to opaque dark gray; blue-gray, or black; May have silvery
iridescence; 2 cleavages at nearly 90° and with striations; H 6
Plagioclase feldspar
Translucent to opaque brown, gray, green, or red; 2 cleavages at
nearly right angles; Exsolution lamellae; H 6
Potassium feldspar (K-spar)
Green to black; Vitreous luster; H 5.5–6.0; 2 cleavages at about 124°
and 56° plus uneven fracture; Usually forms long blades and masses
of needle-like crystals
Actinolite (amphibole)
Dark gray to black; Vitreous luster; H 5.5–6.0; 2 cleavages at about
124° and 56° plus uneven fracture; Forms long crystals that break into
blade-like fragments
Hornblende (amphibole)
HARD
(H > 5.5)
Dark green to black; Dull to vitreous luster; H 5.5–6.0; two cleavages
at nearly right angles (93° and 87°) plus uneven fracture; Forms short
crystals with squarish cross sections; Breaks into blocky fragments
Augite (pyroxene)
Scratches
glass
Transparent or translucent gray, brown, or purple; Greasy luster;
Massive or hexagonal prisms and pyramids; H 7
Quartz
Smoky quartz (black/brown var.),
Amethyst (purple var.)
Not
scratched
by masonry
nail or knife
blade
Gray, black, or colored (dark red, blue, brown) hexagonal prisms with
flat striated ends; H 9
Corundum
Emery (black impure var.),
Ruby (red var.) Sapphire (blue var.)
Opaque red-brown or brown; Luster waxy; Cryptocrystalline; H 7
Transparent to translucent dark red to black; Equant (dodecahedron)
crystal form or massive; H 7
Jasper (variety of quartz)
Garnet
Opaque gray; Luster waxy; Cryptocrystalline; H 7
Opaque black; Luster waxy; Cryptocrystalline; H 7
Black or dark green; Long striated prisms; H 7–7.5
Olive green, Transparent or translucent; No cleavage; Usually has
many cracks and conchoidal to uneven fracture; Single crystals or
masses of tiny crystals resembling green granulated sugar or
aquarium gravel; The crystals have vitreous (glassy) luster
Chert (gray variety of quartz)
Flint (black variety of quartz)
Tourmaline
Olivine
Opaque dark gray to black; Tarnishes gray to rusty yellow-brown;
Cleavage absent; Strongly attracted to a magnet; May be
magnetized; H 6–6.5
Magnetite
Opaque green; Poor cleavage; H 6–7
Opaque brown prisms and cross-shaped twins; H 7
Yellow-brown, brown, or black; vitreous to resinous luster (may also
be submetallic); Dodecahedral cleavage; H 3.5–4.0; Rotten egg smell
when scratched or powdered
Epidote
Staurolite
Sphalerite
Purple cubes or octahedrons; Octahedral cleavage; H 4
Black short opaque prisms; Splits easily along 1 excellent
cleavage into thin sheets; H 2.5–3
Fluorite
Biotite (black mica)
Green short opaque prisms; Splits easily along 1 excellent
cleavage into thin sheets; H 2–3
Chlorite
Opaque rusty brown or yellow-brown; Massive and amorphous;
Yellow-brown streak; H 1–5.5
Limonite
Rusty brown to red-brown, may have shades of tan or white; Earthy
and opaque; Contains pea-sized spheres that are laminated
internally; H 1–5; Pale brown streak
Bauxite
Deep blue; Crusts, small crystals, or massive; Light blue streak;
H 3.5–4
Azurite
Opaque green or gray-green; Dull or silky masses or asbestos;
White streak; H 2–5
Serpentine
Opaque green in laminated crusts or massive; Streak pale green;
Effervesces in dilute HCI; H 3.5–4
Malachite
Translucent or opaque dark green; Can be scratched with your
fingernail; Feels greasy or soapy; H 1
Talc
Transparent or translucent green, brown, blue, or purple; Brittle
hexagonal prisms; Conchoidal fracture; H 5
Apatite
Opaque earthy brick red to dull red-gray, or gray; H 1.5–5;
Red-brown streak; Magnet may attract the gray forms
Hematite
Cleavage
excellent
or good
Cleavage
absent,
poor, or
not visible
Cleavage
excellent
or good
SOFT
(H < 5.5)
Does not
scratch glass
Scratched by
masonry nail
or knife
blade
Cleavage
absent,
poor, or
not visible
FIGURE 3.19 Identification chart for dark to medium-colored minerals with nonmetallic (NM) luster on freshly broken surfaces.
Mineral Properties, Identification, and Uses
■
91
LIGHT-COLORED NONMETALLIC (NM) MINERAL IDENTIFICATION
STEP 1:
What is the
mineral’s
hardness?
STEP 2:
What is
the
mineral’s
cleavage?
STEP 3:
Compare the mineral’s
physical properties to other
distinctive properties below.
STEP 4:
Find mineral name(s) and
check the mineral
database for additional
properties (Figure 3.21).
White or pale gray; 2 good cleavages at nearly 90° plus uneven
fracture; May have striations; H 6
Plagioclase feldspar
Orange, pink, pale brown, green, or white; H 6; 2 good cleavages at
90° plus uneven fracture; exsolution lamellae
Potassium feldspar
Pale brown, white, or gray; Long slender prisms; 1 excellent
cleavage plus fracture surfaces; H 6–7
Sillimanite
Blue, very pale green, white, or gray; Crystals are blades; H 4–7
Kyanite
Gray, white, or colored (dark red, blue, brown) hexagonal prisms
with flat striated ends; H 9
Corundum vars. ruby (red),
sapphire (blue)
Colorless, white, gray, or other colors; Greasy luster; Massive or
hexagonal prisms and pyramids; Transparent or translucent; H 7
Quartz: vars. rose (pink),
rock crystal (colorless), milky
(white), citrine (amber)
Opaque gray or white; Luster waxy; H 7
Chert (variety of quartz)
Colorless, white, yellow, light brown, or pastel colors; Translucent or
opaque; Laminated or massive; Cryptocrystalline; Luster waxy; H 7
Chalcedony
(variety of quartz)
Pale green to yellow; Transparent or translucent; H 7; No cleavage;
Usually has many cracks and conchoidal to uneven fracture; Single
crystals or masses of tiny crystals resembling green or yellow
granulated sugar or aquarium gravel; Crystals vitreous (glassy)
Olivine
Colorless, white, yellow, green, pink, or brown; 3 excellent cleavages;
Breaks into rhombohedrons; Effervesces in dilute HCI; H 3
Calcite
Colorless, white, gray, creme, or pink; 3 excellent cleavages;
Breaks into rhombohedrons; Effervesces in dilute HCI only if
powdered; H 3.5–4
Dolomite
Colorless or white with tints of brown, yellow, blue, black; Short
tabular crystals and roses; Very heavy; H 3–3.5
Barite
Transparent, colorless to white; H 2, easily scratched with your
fingernail; White streak; Blade-like crystals or massive
Gypsum var. selenite
Colorless, white, gray, or pale green, yellow, or red; Spheres of
radiating needles; Luster silky; H 5–5.5
Natrolite (zeolite)
Colorless, white, yellow, blue, brown, or red; Cubic crystals; Breaks
into cubes; Salty taste; H 2.5
Halite
SOFT
(H < 5.5)
Colorless, purple, blue, gray, green, yellow; Cubes with octahedral
cleavage; H 4
Fluorite
Does not
scratch glass
Colorless, yellow, brown, or red-brown; Short opaque prisms;
Splits along 1 excellent cleavage into thin flexible transparent
sheets; H 2–2.5
Muscovite (white mica)
White, gray or yellow; Earthy to pearly; massive form; H 2, easily
scratched with your fingernail; White streak
Gypsum var. alabaster
White to gray; Fibrous form with silky or satiny luster; H 2, easily
scratched with your fingernail
Gypsum var. satin spar
Yellow crystals or earthy masses; Luster greasy; H 1.5–2.5; Smells
like rotten eggs when powdered
Sulfur (Native sulfur)
Opaque pale blue to blue-green; Conchoidal fracture; H 2-4;
Massive or amorphous earthy crusts; Very light blue streak
Chrysocolla
Opaque green, yellow, or gray; Dull or silky masses or asbestos;
White streak; H 2–5
Serpentine
Opaque white, gray, green, or brown; Can be scratched with
fingernail; Greasy or soapy feel; H 1
Talc
Opaque earthy white to very light brown masses of “white clay”;
H 1–2; Powdery to greasy feel
Kaolinite
Mostly pale brown to tan or white; Earthy and opaque; Contains
pea-sized spheres that are laminated internally; H 1–5; Pale brown
to white streak
Bauxite
Colorless to white, orange, yellow, blue, gray, green, or red; May
have internal play of colors; H 5.0–5.5; Amorphous; Often has many
cracks; Conchoidal fracture
Opal
Colorless or pale green, brown, blue, white, or purple; Brittle
hexagonal prisms; Conchoidal fracture; H 5
Apatite
Cleavage
excellent or
good
HARD
(H > 5.5)
Scratches
glass
Not scratched
by masonry
nail or knife
blade
Cleavage
absent,
poor, or
not visible
Cleavage
excellent or
good
Scratched by
masonry nail
or knife blade
Cleavage
absent,
poor, or
not visible
FIGURE 3.20 Identification chart for light-colored minerals with nonmetallic (NM) luster on freshly broken surfaces.
92
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L A B O R AT O R Y 3
MINERAL DATABASE (Alphabetical Listing)
Mineral
ACTINOLITE
(amphibole)
Luster and
Hardness
Crystal
System
Nonmetallic
(NM)
5.5–6
Distinctive
Properties
Streak
White
Monoclinic
Some Uses
Color dark green or pale green;
Forms needles, prisms, and
asbestose fibers; Good cleavage
at 56° and 124°; SG = 3.1
Green gem varieties are
the gemstone “nephrite
jade”; asbestos products
Color pale or dark green, brown, blue,
white, or purple; Sometimes colorless;
Transparent or opaque; Brittle;
Conchoidal fracture; Forms hexagonal
prisms; SG = 3.1–3.4
Used mostly to make
fertilizer, pesticides;
Transparent varieties
sold as gemstones
AMPHIBOLE: See HORNEBLENDE and ACTINOLITE
APATITE
Ca5F(PO4)3
calcium
fluorophosphate
Nonmetallic
(NM)
5
White
Hexagonal
ASBESTOS: fibrous varieties of AMPHIBOLE and SERPENTINE
AUGITE
(pyroxene)
calcium
ferromagnesian
silicate
Nonmetallic
(NM)
AZURITE
Cu3(CO3)2(OH)2
copper carbonate
hydroxide
Nonmetallic
(NM)
5.5–6
White to
pale gray
Color dark green to brown or black;
Forms short, 8-sided prisms; Two
good cleavages that intersect at 87°
and 93° (nearly right angles);
SG = 3.2–3.5
Ore of lithium, used to
make lithium batteries,
ovenware glazes, high
temperature grease, and
to treat depression
3.5–4
Light blue
Color a distinctive deep blue;
Forms crusts of small crystals,
opaque earthy masses, or short
and long prisms; Brittle; Effervesces
in dilute HCI; SG = 3.7–3.8
Ore of copper used to
make pipes, electrical
wire, coins, ammunition,
bronze, brass; added to
vitamin pills for healthy
hair and skin; Gemstone
3–3.5
White
Colorless to white, with tints of
brown, yellow, blue, or red; Forms
short tabular crystals and
rose-shaped masses (Barite roses);
Brittle; Cleavage good to excellent;
Very heavy, SG = 4.3–4.6
Ore of barium, used to
harden rubber, make
fluorescent lamp
electrodes, and in fluids
used to drill oil/gas wells
1–3
White
Brown earthy rock with shades of
gray, white, and yellow; Amorphous;
Often contains rounded pea-sized
structures with laminations;
SG = 2.0–3.0
Ore of aluminum used to
make cans, foil, airplanes,
solar panels; Ore of
gallium used to make LED
bulbs and liquid crystal
displays in cell phones,
computers, flat screen
televisions
Gray-brown
to white
Color black, green-black, or
brown-black; Cleavage excellent;
Forms very short prisms that
split easily into very thin,
flexible sheets; SG = 2.7–3.1
Used for fire-resistant
tiles, rubber, paint
3
Dark gray
to black
Color brownish bronze; Tarnishes bright
purple, blue, and/or red; May be weakly
attracted to a magnet; H 3; Cleavage
absent or poor; Forms dense brittle
masses; Rarely forms crystals
Ore of copper, used to
make pipes, electrical
wire, coins, ammunition,
bronze, brass; added to
vitamin pills for healthy
hair and skin
3
White
Usually colorless, white, or yellow, but
may be green, brown, or pink; Opaque
or transparent; Excellent cleavage in 3
directions not at 90°; Forms prisms,
rhombohedrons, or scalenohedrons that
break into rhombohedrons; Effervesces
in dilute HCI; SG = 2.7
Used to make antacid
tablets, fertilizer, cement;
Ore of calcium
7
White*
Colorless, white, yellow, light
brown, or other pastel colors
in laminations; Often translucent;
Conchoidal fracture; Luster waxy;
Cryptocrystalline; SG = 2.5–2.8
Used as an abrasive;
Used to make glass,
gemstones (agate,
chrysoprase)
Monoclinic
Monoclinic
BARITE
BaSO4
barium sulfate
Nonmetallic
(NM)
Orthorhombic
BAUXITE
Mixture of
aluminum
hydroxides
Nonmetallic
(NM)
No visible
crystals
Nonmetallic
BIOTITE MICA
(NM)
ferromagnesian
potassium, hydrous Monoclinic
aluminum silicate
K(Mg,Fe)3 (Al,Si3O10)(OH,F)2
BORNITE
Cu5FeS4
copper-iron sulfide
Metallic
(M)
2.5–3
Isometric
CALCITE
CaCO3
calcium carbonate
Nonmetallic
(NM)
Hexagonal
CHALCEDONY
SiO2
cryptocrystalline
quartz
Nonmetallic
(NM)
No visible
crystals
*Streak cannot be determined with a streak plate for minerals harder than 6.5. They scratch the streak plate.
FIGURE 3.21 Mineral Database. This is an alphabetical list of minerals and their properties and uses.
Mineral Properties, Identification, and Uses
■
93
MINERAL DATABASE (Alphabetical Listing)
Mineral
CHALCOPYRITE
CuFeS2
copper-iron sulfide
Luster and
Hardness
Crystal
System
Metallic
(M)
3.5–4
Distinctive
Properties
Streak
Some Uses
Dark gray
Color bright silvery gold; Tarnishes
bronze brown, brassy gold, or iridescent
blue-green and red; Brittle; No cleavage;
Forms dense masses or elongate
tetrahedrons; SG = 4.1–4.3
Ore of copper, used to
make pipes, electrical
wire, coins, ammunition,
bronze, brass; added to
vitamin pills for healthy
hair and skin
Tetragonal
CHERT
SiO2
cryptocrystalline
quartz
Nonmetallic
(NM)
No visible
crystals
7
White*
Opaque gray or white; Luster
waxy; Conchoidal fracture;
SG = 2.5–2.8
Used as an abrasive;
Used to make glass,
gemstones
CHLORITE
ferromagnesian
aluminum
silicate
Nonmetallic
(NM)
Monoclinic
2–2.5
White
Color dark green; Cleavage
excellent; Forms short prisms
that split easily into thin
flexible sheets; Luster bright
or dull; SG = 2–3
Used as a “filler” (to take
up space and reduce
cost) in plastics for car
parts, appliances;
Massive pieces carved
into art sculptures
5.5–6
Dark brown
Color silvery black to black; Tarnishes
gray to black; No cleavage; May be
weakly attracted to a magnet; Forms
dense masses or granular masses of
small crystals (octahedrons)
Ore of chromium for
chrome, stainless steel,
mirrors, yellow and green
paint pigments and
ceramic glazes, and pills
for healthy metabolism
and cholesterol levels
Very light
blue
Color pale blue to blue-green; Opaque;
Forms cryptocrystalline crusts or may
be massive; Conchoidal fracture;
Luster shiny or earthy; SG = 2.0–4.0
Ore of copper, used to
make pipes, electrical
wire, coins, ammunition,
bronze, brass; added to
vitamin pills for healthy
hair and skin; Gemstone
2.5–3
Copper
Color copper; Tarnishes brown or green;
Malleable; No cleavage; Forms oddshaped masses, nuggets, or dendritic
forms; SG = 8.8–9.0
Ore of copper, used to
make pipes, electrical
wire, coins, ammunition,
bronze, brass; added to
vitamin pills for healthy
hair and skin
9
White*
Gray, white, black, or colored (red, blue,
brown, yellow) hexagonal prisms with
flat striated ends; Opaque to
transparent; Cleavage absent;
SG = 3.9–4.1 H 9
Used for abrasive
powders to polish lenses;
gemstones (red ruby,
blue sapphire);
emery cloth
3.5–4
White
Color white, gray, creme, or
pink; Usually opaque; Cleavage
excellent in 3 directions; Breaks
into rhombohedrons; Resembles
calcite, but will effervesce in
dilute HCI only if powdered;
SG = 2.8–2.9
Ore of magnesium used
to make paper;
lightweight frames for jet
engines, rockets, cell
phones, laptops; pills for
good brain, muscle, and
skeletal health
6–7
White*
Color pale or dark green to
yellow-green; Massive or forms
striated prisms; Cleavage poor;
SG = 3.3–3.5
Used as a green
gemstone
(Mg,Fe,Al)6(Si,Al)4O10(OH)8
Metallic
CHROMITE
(M)
FeCr2O4
iron-chromium oxide
Isometric
CHRYSOCOLLA
CuSiO3 · 2H2O
hydrated copper
silicate
Nonmetallic
(NM)
COPPER
(NATIVE COPPER)
Cu
copper
Metallic
(M)
CORUNDUM
Al2O3
aluminum oxide
Nonmetallic
(NM)
2–4
Orthorhombic
Isometric
Hexagonal
DOLOMITE
CaMg(CO3)2
magnesian calcium
carbonate
Nonmetallic
(NM)
Hexagonal
EPIDOTE
complex silicate
Nonmetallic
(NM)
Monoclinic
FELDSPAR: See PLAGIOCLASE (Na-Ca Feldspars) and POTASSIUM FELDSPAR (K-Spar)
FLINT
SiO2
cryptocrystalline
quartz
Nonmetallic
(NM)
No visible
crystals
7
White*
Color black to very dark gray;
Opaque to translucent;
Conchoidal fracture; Cryptocrystalline; SG = 2.5–2.8
Used as an abrasive;
Used to make glass;
Black gemstone
FLUORITE
CaF2
calcium fluoride
Nonmetallic
(NM)
4
White
Colorless, purple, blue, gray,
green, or yellow; Cleavage
excellent; Crystals usually
cubes; Transparent or
opaque; Brittle; SG = 3.0–3.3
Ore of fluorine used in
fluoride toothpaste,
refrigerant gases, rocket
fuel
Isometric
*Streak cannot be determined with a streak plate for minerals harder than 6.5. They scratch the streak plate.
FIGURE 3.21 (continued)
94
■
L A B O R AT O R Y 3
MINERAL DATABASE (Alphabetical Listing)
Mineral
GALENA
PbS
lead sulfide
Luster and
Hardness
Crystal
System
Metallic
(M)
2.5
Nonmetallic
(NM)
Color bright silvery gray; Tarnishes dull
gray; Forms cubes and octahedrons;
Brittle; Cleavage good in three
directions, so breaks into cubes;
SG = 7.4–7.6
Ore of lead for television
glass, auto batteries,
solder, ammunition; May
be an ore of bismuth (an
impurity) used as a lead
substitute in pipe solder
and fishing sinkers; May
be an ore of silver (an
impurity) used in jewelry,
electrical circuit boards
White*
Color usually red, black, or brown,
sometimes yellow, green, pink;
Forms dodecahedrons; Cleavage
absent but may have parting; Brittle;
Translucent to opaque; SG = 3.5–4.3
Used as an abrasive;
Red gemstone
5–5.5
Yellow-brown
Color dark brown to black;
Tarnishes yellow-brown; Forms
layers of radiating microscopic
crystals; SG = 3.3–4.3
Ore of iron for iron and
steel used in machines,
buildings, bridges, nails,
tools, file cabinets; Added
to pills and foods to aid
hemoglobin production in
red blood cells
2.5–3.0
Gold-yellow
7
Isometric
GOETHITE
Metallic
FeO(OH)
(M)
iron oxide hydroxide
Orthorhombic
GOLD
(NATIVE GOLD)
Au
pure gold
Metallic
(M)
Isometric
GRAPHITE
C
carbon
Metallic
(M)
Nonmetallic
(NM)
HALITE
NaCl
sodium chloride
Nonmetallic
(NM)
Color dark silvery gray to black; Forms
flakes, short hexagonal prisms, and
earthy masses; Greasy feel; Very
soft; Cleavage excellent in 1
direction; SG = 2.0–2.3
Used for pencils, anodes
(negative ends) of most
batteries, synthetic motor
oil, carbon steel, fishing
rods, golf clubs
2
White
Colorless, white, or gray; Forms
tabular crystals, prisms, blades,
or needles (satin spar variety);
Transparent to translucent; Very
soft; Cleavage good; SG = 2.3
Plaster-of-paris,
wallboard, drywall, art
sculpture medium
(alabaster)
2.5
White
Colorless, white, yellow, blue, brown,
or red; Transparent to translucent;
Brittle; Forms cubes; Cleavage
excellent in 3 directions, so breaks
into cubes; Salty taste; SG = 2.1–2.6
Table salt, road salt;
Used in water softeners
and as a preservative;
Sodium ore
1–6
Red to
red-brown
Color silvery gray, reddish silver, black,
or brick red; Tarnishes red; Opaque;
Soft (earthy) and hard (metallic) varieties
have same streak; Forms thin tabular
crystals or massive; May be attracted
to a magnet; SG = 4.9–5.3
Red ochre pigment in
paint and cosmetics. Ore
of iron for iron and steel
used in machines,
buildings, bridges, nails,
tools, file cabinets; Added
to pills and foods to aid
hemoglobin production in
red blood cells
5.5–6.0
White to
pale gray
Color dark gray to black;
Forms prisms with good cleavage
at 56° and 124°; Brittle; Splintery or
asbestos forms; SG = 3.0–3.3
Fibrous varieties used for
fire-resistant clothing,
tiles, brake linings
Monoclinic
Metallic (M)
or
Nonmetallic
(NM)
Hexagonal
HORNBLENDE
Nonmetallic
(amphibole) calcium (NM)
ferromagnesian
aluminum silicate
Monoclinic
Ductile and malleable
metal used for jewelry;
Electrical circuitry in
computers, cell phones,
car air bags; Heat shields
for satellites
Dark gray
Isometric
HEMATITE
Fe2O3
iron oxide
Color gold to yellow-gold; Does not
tarnish; Ductile, malleable and sectile;
Hackly fracture; SG = 19.3; No cleavage;
Forms odd-shaped masses, nuggets,
and dendritic forms
1
Hexagonal
GYPSUM
CaSO4 · 2H2O
hydrated calcium
sulfate
Some Uses
Gray to
dark gray
Isometric
GARNET
complex silicate
Distinctive
Properties
Streak
JASPER
SiO2
cryptocrystalline
quartz
Nonmetallic
(NM)
No visible
crystals
7
White*
Color red-brown, or yellow; Opaque;
Waxy luster; Conchoidal fracture;
Cryptocrystalline; SG = 2.5–2.8
Used as an abrasive;
Used to make glass,
gemstones
KAOLINITE
Al4(Si4O10)(OH)8
aluminum silicate
hydroxide
Nonmetallic
(NM)
Triclinic
1–2
White
Color white to very light brown;
Commonly forms earthy, microcrystalline
masses; Cleavage excellent but absent in
hand samples; SG = 2.6
Used for pottery, clays,
polishing compounds,
pencil leads, paper
4–7
White*
Color blue, pale green, white, or gray;
Translucent to transparent; Forms
blades; SG = 3.6–3.7
High temperature
ceramics, spark plugs
K-SPAR: See POTASSIUM FELDSPAR
KYANITE
Al2(SiO4)O
aluminum silicate
oxide
Nonmetallic
(NM)
Triclinic
*Streak cannot be determined with a streak plate for minerals harder than 6.5. They scratch the streak plate.
Mineral Properties, Identification, and Uses
■
95
MINERAL DATABASE (Alphabetical Listing)
Mineral
LIMONITE
Fe2O3 · nH2O
hydrated iron oxide
and/or
FeO(OH) · nH2O
hydrated iron oxide
hydroxide
MAGNETITE
Fe3O4
iron oxide
Luster and
Hardness
Crystal
System
Metallic (M)
or
Nonmetallic
(NM)
Streak
Distinctive
Properties
1–5.5
Yellowbrown
Color yellow-brown to dark brown;
Tarnishes yellow to brown;
Amorphous masses; Luster dull or
earthy; Hard or soft; SG = 3.3–4.3
Yellow ochre pigment in paint
and cosmetics. Ore of iron for
iron and steel used in machines,
buildings, bridges, nails, tools,
file cabinets; Added to pills and
foods to aid hemoglobin
production in red blood cells
6–6.5
Dark gray
Color silvery gray to black; Opaque;
Forms octahedrons; Tarnishes gray;
No cleavage; Attracted to a magnet
and can be magnetized; SG = 5.0–5.2
Ore of iron for iron and steel
used in machines, buildings,
bridges, nails, tools, file
cabinets; Added to pills and
foods to aid hemoglobin
production in red blood cells
3.5–4
Green
Color green, pale green, or graygreen; Usually in crusts, laminated
masses, or microcrystals; Effervesces
in dilute HCl; SG = 3.6–4.0
Ore of copper, used to make
pipes, electrical wire, coins,
ammunition, bronze, brass;
added to vitamin pills for healthy
hair and skin; Gemstone
2–2.5
White
Colorless, yellow, brown, or redbrown; Forms short opaque prisms;
Cleavage excellent in 1 direction, can
be split into thin flexible transparent
sheets; SG = 2.7–3.0
Computer chip substrates,
electrical insulation, roof
shingles, Cosmetics with a
satiny sheen
5–5.5
White
Colorless, white, gray, or pale
green, yellow, or red; Forms
masses of radiating needles;
Silky luster; SG = 2.2–2.4
Used in water softeners
7
White*
Color pale or dark olive-green to
yellow, or brown; Forms short crystals
that may resemble sand grains;
Conchoidal fracture; Cleavage absent;
Brittle; SG = 3.3–3.4
Green gemstone (peridot); Ore
of magnesium used to make
paper; lightweight frames for
jet engines, cell phones,
laptops; pills for good brain,
muscle, and skeletal health
5–5.5
White
Colorless to white, orange, yellow,
brown, blue, gray, green, or red; may
have play of colors (opalescence);
Amorphous; Cleavage absent;
Conchoidal fracture; SG = 1.9–2.3
Gemstone
6
White
Colorless, white, gray, or black; May
have iridescent play of color from
within; Translucent; Forms striated
tabular crystals or blades; Cleavage
good in two directions at nearly 90°;
SG = 2.6–2.8
Used to make ceramics, glass,
enamel, soap, false teeth,
scouring powders
6
White
Color orange, brown, white, green,
or pink; Forms translucent prisms
with subparallel exsolution lamellae;
Cleavage excellent in two directions
at nearly 90°; SG = 2.5–2.6
Used to make ceramics, glass,
enamel, soap, false teeth,
scouring powders
6–6.5
Dark gray
Color silvery gold; Tarnishes brown;
H 6–6.5; Cleavage absent to poor;
Brittle; Forms opaque masses, cubes
(often striated), or pyritohedrons;
SG = 4.9–5.2
Ore of sulfur for matches,
gunpowder, fertilizer, rubber
hardening (car tires), fungicide,
insecticide, paper pulp
processing
3.5–4.5
Dark gray
to black
Color brassy to brown-bronze;
Tarnishes dull brown, sometimes with
faint iridescent colors; Fracture
uneven to conchoidal; No cleavage;
attracted to a magnet; SG = 4.6
Ore of iron and sulfur; Impure
forms contain nickel and are
used as nickel ore; the nickel is
used to make stainless steel
Amorphous
Metallic (M)
or
Nonmetallic
(NM)
Isometric
MALACHITE
Cu2CO3(OH)2
copper carbonate
hydroxide
Nonmetallic
(NM)
Some Uses
Monoclinic
MICA: See BIOTITE and MUSCOVITE
Nonmetallic
MUSCOVITE MICA
(NM)
potassium hydrous
aluminum silicate
KAl2(Al,Si3O10)(OH,F)2
Monoclinic
NATIVE COPPER: See COPPER
NATIVE GOLD: See GOLD
NATIVE SILVER: See SILVER
NATIVE SULFUR: See SULFUR
Nonmetallic
NATROLITE
(NM)
(ZEOLITE)
Na2(Al2Si3O10) · 2H2O
hydrous sodium
Orthorhombic
aluminum silicate
OLIVINE
(Fe,Mg)2SiO4
ferromagnesian
silicate
Nonmetallic
(NM)
Orthorhombic
OPAL
SiO2 · nH2O
hydrated silicon
dioxide
PLAGIOCLASE
FELDSPAR
NaAlSi3O8 to
CaAl2Si2O8
calcium-sodium
aluminum silicate
Nonmetallic
(NM)
Amorphous
Nonmetallic
(NM)
Triclinic
Nonmetallic
POTASSIUM
(NM)
FELDSPAR
KAlSi3O8
potassium aluminum
Monoclinic
silicate
PYRITE
(“fool’s gold”)
FeS2
iron sulfide
Metallic
(M)
PYRRHOTITE
Metallic
(M)
FeS
iron sulfide
Isometric
Monoclinic
*Streak cannot be determined with a streak plate for minerals harder than 6.5. They scratch the streak plate.
96
■
L A B O R AT O R Y 3
MINERAL DATABASE (Alphabetical Listing)
Mineral
Luster and
Crystal
Hardness
System
Distinctive
Properties
Streak
Some Uses
PYROXENE: See AUGITE
QUARTZ
SiO2
silicon dioxide
Nonmetallic
(NM)
7
White*
Hexagonal
Usually colorless, white, or gray but
uncommon varieties occur in all colors;
Transparent to translucent; Luster
greasy; No cleavage; Forms hexagonal
prism and pyramids; SG = 2.6–2.7
Used as an abrasive;
Used to make glass,
gemstones
Some quartz varieties are:
• var. flint (opaque black or dark gray)
• var. smoky (transparent gray)
• var. citrine (transparent yellow-brown)
• var. amethyst (purple)
• var. chert (opaque gray)
• var. milky (white)
• var. jasper (opaque red or yellow)
• var. rock crystal (colorless)
• var. rose (pink)
• var. chalcedony (translucent, waxy
luster)
SERPENTINE
Mg6Si4O10(OH)8
magnesium silicate
hydroxide
Nonmetallic
(NM)
SILLIMANITE
Al2(SiO4)O
aluminum silicate
Nonmetallic
(NM)
2–5
White
Color pale or dark green, yellow,
gray; Forms dull or silky masses
and asbestos forms; No cleavage;
SG = 2.2–2.6
Fibrous varieties used for
fire-resistant clothing,
tiles, brake linings
6–7
White
Color pale brown, white, or gray;
One good cleavage plus fracture
surfaces; Forms slender prisms
and needles; SG = 3.2
High-temperature
ceramics
2.5–3.0
White to
silvery white
Color silvery white to gray; Tarnishes
dark gray to black; Ductile, malleable
and sectile; Hackly fracture; No
cleavage; Forms nuggets, curled
wires, and dendritic forms; SG = 10.5
Ductile and malleable
metal used for jewelry and
silverware; Electrical circuit
boards for computers and
cell phones; Photographic
film
3.5–4
White to pale
yellow-brown
Color silvery yellow-brown, dark red,
or black; Tarnishes brown or black;
Dodecahedral cleavage excellent to
good; Smells like rotten eggs when
scratched/powdered; Forms
misshapen tetrahedrons or
dodecahedrons; SG = 3.9–4.1
Ore of zinc for brass,
galvanized steel and
roofing nails, skin-healing
creams, pills for healthy
immune system and
protein production: Ore of
Indium (an impurity) used
to make solar cells
7
White to
gray*
Color brown to gray-brown; Tarnishes
dull brown; Forms prisms that
interpenetrate to form natural crosses;
Cleavage poor; SG = 3.7–3.8
Gemstone crosses
called “fairy crosses”
Pale yellow
Color bright yellow; Forms
transparent to translucent
crystals or earthy masses;
Cleavage poor; Luster greasy to
earthy; Brittle; SG = 2.1
Used for matches,
gunpowder, fertilizer, rubber
hardening (car tires),
fungicide, insecticide,
paper pulp processing
1
White
Color white, gray, pale green, or
brown; Forms cryptocrystalline
masses that show no cleavage;
Luster silky to greasy; Feels
greasy or soapy (talcum powder);
Very soft; SG = 2.7–2.8
Used as a “filler” (to take
up space and reduce cost)
in plastics for car parts,
appliances; Massive
pieces carved into art
sculptures
7–7.5
White*
Color usually opaque black or green,
but may be transparent or
translucent green, red, yellow, pink
or blue; Forms long striated prisms
with triangular cross sections;
Cleavage absent; SG = 3.0–3.2
Crystals used in radio
transmitters; gemstone
Monoclinic
Orthorhombic
SILVER
(NATIVE SILVER)
Ag
pure silver
Metallic
(M)
SPHALERITE
ZnS
zinc sulfide
Metallic (M)
or
Nonmetallic
(NM)
Isometric
Isometric
STAUROLITE
iron magnesium
zinc aluminum
silicate
Nonmetallic
(NM)
SULFUR
(NATIVE SULFUR)
S
sulfur
Nonmetallic
(NM)
TALC
Mg3Si4O10(OH)2
hydrous magnesian
silicate
Monoclinic
1.5–2.5
Orthorhombic
Nonmetallic
(NM)
Monoclinic
TOURMALINE
complex silicate
Nonmetallic
(NM)
Hexagonal
ZEOLITE: A group of calcium or sodium hydrous aluminum silicates. See NATROLITE.
*Streak cannot be determined with a streak plate for minerals harder than 6.5. They scratch the streak plate.
Mineral Properties, Identification, and Uses
■
97
2012 U.S. NET IMPORT RELIANCE ON SELECTED NON-FUEL MINERAL COMMODITIES
COMMODITY
(Element, Ore, or
Raw Mineral)
ORE MINERAL
or
RAW MINERAL
Percent
Import
Reliance
Fluorine ore (F):
fluorspar
Fluorite
100
Graphite (C)
Graphite
100
Indium metal (In)
100
Mica (sheet)
Sphalerite with In
as an impurity
Muscovite
Quartz crystal
(industrial)
Niobium metal
(Nb, “columbium”)
Quartz var. rock
crystal
Columbite (in
“coltan”)
100
Tantalum metal
(Ta)
Tantalite (in
“coltan”)
100
Gallium metal
(Ga)
Bauxite is Ga ore
99
Vanadium metal
(V)
Magnetite with V
as an impurity
96
Bismuth metal
(Bi)
Galena with Bi as
an impurity
92
Bismuth is used as a nontoxic replacement for lead (in ceramic glazes,
fishing sinkers, food processing equipment, plumbing, and shot for hunting)
and in antidiarrheal medications.
Barium metal ore
(Ba)
Zinc metal (Zn)
Barite
80
Sphalerite is an
ore of Zn
72
Barium (Ba) is widely used to make capacitors (that store energy) and
memory cells in cell phones and other portable electronic devices.
Zinc is used to make alloys like brass, skin-healing creams, and galvanized
(rust-proof) steel and roofing nails; added to vitamin pills for a healthy
immune system and to aid protein production.
Chromium metal
(Cr)
Chromite is an ore
of Cr
70
Chromium is used to make stainless steel, yellow and green ceramic glazes
and paints, and military camouflage paints; added to vitamin pills for healthy
metabolism and lower cholesterol levels.
Garnet (industrial)
Garnet
65
Silver metal (Ag)
Native silver; Galena
with Ag as an impurity
Pyrrhotite contains Ni
as an impurity
57
Industrial garnet is used as an abrasive in things like sandpaper and
sandblasting.
Silver is used to make jewelry and silverware, photographic film, and solder
on electrical circuit boards of computers and cell phones.
49
Nickel is used to make rechargeable batteries (Ni-Cd) for portable electronic
devices, screw-end caps of light bulbs, and stainless steel.
Magnesium
metal (Mg)
Dolomite and
Olivine are Mg ores
46
Magnesium is used to make strong, lightweight frames for jet engines and
rockets, lightweight cell phone and laptop cases, and incendiary flares and
bombs; added to vitamin pills to aid good brain and muscle function and
strengthen bones.
Tungsten metal
(W)
Wolframite is W
ore
42
Tungsten is a dense metal that makes cell phones and pagers vibrate (by
attaching it to an electric motor spinning off center); also used for light bulb
filaments, golf clubs, and tungsten carbide cutting tools.
Copper metal
(Cu)
35
Aluminum (Al)
Azurite, Bornite,
Chalcopyrite,
Chrysocolla, and
Malachite are Cu ores
Bauxite is Al ore
Salt
Halite
19
Sulfur (S)
Native Sulfur;
Pyrite is a S ore
19
Copper is used to make copper pipes; electrical wire for homes, businesses,
electric motors, and circuit boards in cell phones and other electrical
devices. Hybrid cars contain about 100 pounds (45 kg) of copper. Added to
vitamin pills for healthy hair and skin.
Aluminum is a lightweight silvery metal used to make drink cans, foil,
airplanes, and solar panels.
Used as table salt, road salt (to melt snow), in water softeners, and as a food
preservative.
Used to make matches, gunpowder, fertilizer, fungicide, insecticide, and
harden rubber (car tires).
Nickel metal (Ni)
100
100
20
WHAT IS THIS COMMODITY USED FOR?
Fluorine is used in fluoride toothpaste, fluorocarbon refrigerant gases and
fire extinguishers, and fluoropolymer plastics that coat non-stick fry pans
and insulate wiring in cell phones, laptops, and airplanes.
Used to make carbon steel, pencils, carbon fiber reinforced plastics in car
bodies, and negative ends of most batteries (including those in all cell
phones, power tools, computers, and hybrid/electric vehicles).
Indium is used to make solar cells, and liquid-crystal displays (LCDs) in cell
phones, computers, and flat-screen television sets.
Muscovite is used in heating elements of hair dryers and toasters, joint
compound, and cosmetics with a satiny or glittery sheen.
Crystals of cultured pure quartz are used to make quartz watches and the
frequency controls and timers in every computer and cell phone.
Niobium is used to make high-strength non-corrosive steel alloys (for jet
engines, power plants) and arc welding rods, plus electrical insulation
coatings in cell phones, computers, and electronic games.
Tantalum is used to make “tantalum capacitors” that buffer the flow of
electricity between a battery and electronic parts in the circuits of cell
phones, laptops, iPods, and most other electrical devices.
Gallium is used to make light-emitting diode (LED) bulbs and liquid-crystal
displays (LCDs) in things like cell phones, computers, and flat-screen
television sets.
Vanadium is used for cutting tools; mixed with iron to make lightweight
shock-resistant steel for car axles and gears, springs, and cutting tools.
Gypsum
Gypsum
12
Used to make Plaster-of-Paris, drywall and for art (alabaster).
Iron metal (Fe),
Steel
Geothite, Limonite,
Magnetite, and Hematite
are Fe ores
11
Iron and steel a…