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CHAPTER 3
Date
Minerals of the Earth’s Crust
SECTION
1 What Is a Mineral?
BEFORE YOU READ
After you read this section, you should be able to answer
these questions:
• What are minerals?
• What determines the shape of a mineral?
• What are two main groups of minerals?
What Are Minerals?
A mineral is a naturally formed, inorganic solid that
forms crystals and is always made of the same elements.
The figure below shows four questions that you can ask
in order to learn whether something is a mineral.
Is it nonliving?
Minerals are inorganic.
This means that they are
not made of living things
or their remains.
STUDY TIP
Learn New Words As you
read, underline words you
don’t understand. When you
figure out what they mean,
write the words and their
definitions in your notebook.
Does it have a
crystalline structure?
Minerals are crystals.
Each mineral has a
certain crystal structure
that is always the same.
Is it a solid?
Minerals are not
gases or liquids.
Does it form
naturally?
Minerals are not
made by people.
All minerals have four
features, as described
in the figure.
TAKE A LOOK
1. Explain Why are
diamonds that are made
by people not considered
minerals?
Critical Thinking
2. Apply Concepts Coal is
made from the remains of
dead plants. Is coal a mineral?
Explain your answer.
You might not be familiar with the term “crystalline
structure.” To understand what crystalline structure is, you
need to know a little about how elements form minerals.
Elements are pure substances that cannot be broken down
into simpler substances. Oxygen, chlorine, carbon, and iron
are examples of elements. Elements can come together in
certain ways to form new substances, such as minerals. All
minerals are made of one or more elements.
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Minerals of the Earth’s Crust
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SECTION 1
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Date
What Is a Mineral? continued
COMPOUNDS AND ATOMS
READING CHECK
3. Define What is a
compound?
Most minerals are made of compounds of several different elements. A compound is a substance made of
two or more elements that are chemically bonded. For
example, the mineral halite is a compound of sodium, Na,
and chlorine, Cl. A few minerals, such as gold and silver,
are made of only one element. A mineral that is made of
only one element is called a native element.
Each element is made of only one kind of atom. An
atom is the smallest part of an element that has the properties of that element. Like other compounds, minerals
are made up of atoms of one or more elements.
CRYSTALS
READING CHECK
4. Explain What causes
minerals to form crystals?
Remember that minerals have a definite crystalline
structure. This means that the atoms in the mineral line
up in a regular pattern. The regular pattern of the atoms
in a mineral causes the mineral to form crystals. Crystals
are solid, geometric forms of minerals that are formed by
repeating a pattern of atoms.
The shape of a crystal depends on how the atoms in it
are arranged. The atoms that make up each mineral are
different. However, there are only a few ways that atoms
can be arranged. Therefore, the crystals of different minerals can have similar shapes.
Although different minerals may form similar shapes,
each mineral forms only one shape of crystal. Therefore,
geologists say that a mineral has a definite crystalline
structure. This means that crystals of a certain mineral
always form the same shape.
The mineral gold is made of atoms of the element
gold. The atoms are arranged in a cubic pattern.
TAKE A LOOK
5. Identify What shape are
gold crystals?
Crystals of gold form
cubes because of the way
their atoms are arranged.
Real crystals of gold may
not be perfect cubes
because the crystals may
be damaged or not form
completely. However, the
atoms are still arranged in
a cubic pattern.
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Minerals of the Earth’s Crust
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SECTION 1
Class
Date
What Is a Mineral? continued
How Do Geologists Classify Minerals?
Geologists classify minerals based on the elements or
compounds in the minerals. Two main groups of minerals
are silicate minerals and nonsilicate minerals.
SILICATE MINERALS
Silicon and oxygen are two of the most common elements
in the Earth’s crust. Minerals that contain compounds of
silicon and oxygen are called silicate minerals. Silicate
minerals make up more than 90% of the Earth’s crust.
Most silicate minerals also contain elements other than
silicon and oxygen, such as aluminum, iron, or magnesium.
Common Silicate Minerals
TAKE A LOOK
6. Identify What two
elements are found in all of
the minerals in the figure?
Explain your answer.
Quartz is a mineral
that is found in many
rocks of the Earth’s
crust.
Mica breaks into
sheets easily.
Feldspar is also common in the
rocks of the Earth’s crust. Feldspar
can contain many elements other
than silicon and oxygen, such as
potassium or sodium.
NONSILICATE MINERALS
Minerals that do not contain compounds of silicon and
oxygen are called nonsilicate minerals. Some of these
minerals are made of elements such as carbon, oxygen,
fluorine, and sulfur.
Types of Nonsilicate Minerals
Native elements are
minerals that are
made of only one
element. Copper, gold,
silver, and diamonds
are native elements.
Carbonates are
minerals that contain
compounds of carbon
and oxygen. Calcite is a
carbonate mineral.
Halides are minerals that contain the
elements fluorine,
chlorine, iodine, or
bromine. Fluorite
and halite are halide
minerals.
Copper
Calcite
Fluorite
Oxides are minerals
that contain compounds of oxygen and
another element, such
as iron or aluminum.
Rubies and sapphires Corundum
are forms of the mineral corundum, which
is an oxide mineral.
Sulfates are minerals
that contain compounds
of oxygen and sulfur.
Gypsum is a sulfate
Gypsum
mineral.
Sulfides are minerals that
contain compounds of
sulfur and an element
other than oxygen, such as
lead, iron, or nickel. Galena
and pyrite (“fool’s gold”)
are sulfide minerals.
TAKE A LOOK
7. Compare How are
sulfate minerals different
from sulfide minerals?
Galena
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Minerals of the Earth’s Crust
Name
Class
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Section 1 Review
SECTION VOCABULARY
compound a substance made up of atoms of
two or more different elements joined by
chemical bonds
crystal a solid whose atoms, ions, or molecules
are arranged in a regular, repeating pattern
element a substance that cannot be separated
or broken down into simpler substances by
chemical means
mineral a naturally formed, inorganic solid that
has a definite chemical structure
nonsilicate mineral a mineral that does not
contain compounds of silicon and oxygen
silicate mineral a mineral that contains a
combination of silicon and oxygen and that
may also contain one or more metals
1. Identify What are four features of a mineral?
2. Compare What is the difference between an atom and an element?
3. Infer What determines the shape of a crystal?
4. Apply Concepts Why is the ice in a glacier considered a mineral, but the water in a
river is not considered a mineral?
5. Describe What are the features of the two major groups of minerals?
6. List Give four types of nonsilicate minerals.
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Minerals of the Earth’s Crust
Earth Science Answer Key continued
4. at the poles
5. the prime meridian and the 180° meridian
2. If two contour lines crossed, the point at
SECTION 2 MAPPING THE EARTH’S
SURFACE
3.
1. Moving information from a curved surface
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
4.
5.
6.
to a flat surface causes distortions.
a way of transferring information from a
globe to a flat surface
Longitude lines are equally spaced. Latitude
lines are unequally spaced.
The cone touches the globe at each line of
longitude.
north and south
The poles represent natural points at which
a plane can touch the Earth’s surface.
at the point of contact
Road maps are often used to show distances. Equal-area projections show distances accurately.
shape
in symbols
Texas
so that people can interpret the symbols on
the map
gathering information on a place without
touching it
about 262 km
a system of satellites that orbit Earth
Orbit Earth and send signals to the surface.
a system on a computer that shows information about an area
Review
1. lines on a map that connect points of equal
elevation
2. Maps of areas with high relief have large
contour intervals. Maps of areas with little
relief have small contour intervals.
3. Feature
Color on a topographic map
6.
Contour lines
brown
Bodies of water
blue
Major roads
red
Buildings and bridges
black
Wooded areas
green
Cities
gray or red
4. elevation, bodies of water, major roads,
bridges, railroad tracks
5. about 145 m
6. a closed circle
Chapter 3 Minerals of the
Earth’s Crust
SECTION 1 WHAT IS A MINERAL?
1. Minerals form naturally.
2. It is not a mineral, because it is not inorganic.
3. a substance made of two or more elements
Review
1. Both show the features of the Earth’s sur-
2.
3.
4.
5.
which they crossed would have to have two
elevations. It is not possible for one point to
have more than one elevation.
the change in elevation between two
contour lines
50 m
colors and symbols
gentle, steep, higher
face as they would appear if they were
projected on a curved piece of paper.
Cylindrical projections project the features
onto a cylinder. Conic projections project
the features onto a cone.
title, scale, indicator of direction, legend, date
equal-area projection
conic projection
Radar can penetrate thick clouds and collect
images of the land beneath.
satellites, GPS, GIS
4.
5.
6.
7.
bound together
the regular pattern of atoms that make them up
cubes
All are silicate minerals, so all contain
silicon and oxygen.
Sulfate minerals contain compounds of
sulfur and oxygen; sulfide minerals contain
compounds of sulfur and another element.
Review
1. solid, inorganic, crystalline, naturally formed
2. An atom is the smallest part of an element that
SECTION 3 TOPOGRAPHIC MAPS
has all the qualities of that element. Elements
are made up of only one kind of atom.
1. the height of a point above sea level
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Earth Science
Earth Science Answer Key continued
9. These appliances run on electricity. If
3. The crystal’s shape is determined by the
electricity couldn’t move through them
easily, they might not work correctly.
10. calcite, quartz
11. impurities
arrangement of atoms or molecules in the
crystal.
4. Water is not a solid.
5. Silicate minerals contain compounds of silicon and oxygen. Nonsilicate minerals do not
contain compounds of silicon and oxygen.
6. native elements, oxides, sulfides, sulfates,
halides, carbonates
Review
1. An ore is a rock or mineral that has enough
useful material in it to be mined at a profit.
2.
SECTION 2 IDENTIFYING MINERALS
1. It can react with air or water.
2. A mineral’s color may change, but its streak
3.
4.
5.
6.
7.
is always the same.
conchoidal
19 times
the resistance of a mineral to being
scratched
No, because orthoclase is harder than apatite.
They glow.
3.
4.
5.
Main features
Common objects
made from it
Metal
has shiny surfaces, wires, cars,
does not transmit
electronics
light, transmits
heat and electricity
easily, can be rolled
into sheets or
stretched into wires
Nonmetal
has shiny or dull
surfaces, does not
transmit heat or
electricity easily,
transmits light
cement,
computer chips,
glass
3. evaporation, metamorphism, deposition
4. Open-pit mines: gold
Review
1. Minerals with cleavage break along smooth,
2.
Type of
material
Quarries: gravel
Strip mines: coal
flat surfaces. Minerals with fracture break
along curved or irregular surfaces.
The same mineral can have many different
colors.
hardness, streak, cleavage or fracture, luster,
density
The mineral’s hardness is probably about 4.
Calcite has a hardness of 3. Apatite has a
hardness of 5. Since apatite scratches the
mineral but calcite doesn’t, the mineral’s
hardness must be somewhere between 3 and 5.
2.6
Chapter 4 Rocks: Mineral
Mixtures
SECTION 1 THE ROCK CYCLE
1. limestone, granite
2. Weathering causes rock to break down into
smaller pieces.
3. water, wind, ice, gravity
4. Igneous rocks form when melted rock
SECTION 3 THE FORMATION, MINING,
AND USE OF MINERALS
5.
1. Metamorphism: garnet, graphite, talc
Reaction: gold, copper, pyrite
gold, copper
iron, coal, salt
horizontal, vertical, angled
pollution and habitat destruction
When mineral materials are recycled, less
of the minerals have to be mined from the
Earth.
7. Silver: electronics, jewelry
Bauxite: aluminum cans, utensils
8. ilmenite, magnetite, bauxite, beryl
6.
7.
8.
2.
3.
4.
5.
6.
9.
cools. Metamorphic rocks form when
rock is heated (but does not melt) and its
composition changes.
One possible path: Sedimentary rocks melt
and cool to form igneous rocks.
by studying its features
45%
the sizes of the sediment particles it is
formed from
when melted rock cools slowly underground
Review
1. Weathering is the process by which water,
wind, ice, and heat break down rock.
Erosion is the process by which sediment is
transported from its source.
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Earth Science