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Minerals of the Earth’s Crust

Section 1 What Is a Mineral?

Section 2 Identifying Minerals

Section 3 The Formation, Mining, and Use of Minerals

Chapter 3

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Concept Mapping


Section 1 What Is a Mineral?

Bellringer

Compare the piece of pencil lead and the diamond in

the photograph provided by your teacher. Both

substances are composed of carbon. How can the

same element form two substances with such different

properties?

Record your response in your science journal.

Chapter 3


Section 1 What Is a Mineral?Chapter 3

• Describe the structure of minerals.

• Describe the two major groups of minerals.

Objectives



Mineral Structure

• A mineral is a naturally formed, inorganic solid

that has a definite crystalline structure.

• You can tell whether an object is a mineral by

asking four questions.



Mineral Structure, continued

• Is it a nonliving material?

• Is it a solid?

• Does it have a crystalline structure?

• Is it formed in nature?




• To understand what a crystalline structure is, you

need to know a little about the elements that make

up a mineral.

• Elements are pure substances that cannot be

separated or broken down into simpler substances

by chemical means.



Elements

Click below to watch the Visual Concept.

Visual Concept

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• Atoms and Compounds Minerals may be either

elements or compounds.

• A compound is a substance made of atoms of

two or more different elements joined by chemical

bonds.



Compounds


Visual Concept

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• A mineral that is composed of only one element is

called a native element.

• Gold and silver are examples of native elements.




• Solid, geometric forms of minerals produced by a

repeating pattern of atoms that is present through-

out the mineral are called crystals.

• A crystal’s shape is determined by the arrangement

of the atoms within the crystal.

• The arrangement of atoms in turn is determined by

the kinds of atoms that make up the mineral.



Two Groups of Minerals

• Minerals are divided into two groups based on their

chemical composition.

• Silicate minerals are minerals that contain a

combination of silicon, oxygen, and one or more

metals.

• Examples of silicate minerals are quartz, feldspar,

and mica.



Two Groups of Minerals, continued

• Nonsilicate minerals are minerals that do not

contain compounds of silicon and oxygen. There

are six main classes of nonsilicate minerals.

• Native Elements

• Carbonates

• Halides

• Oxides

• Sulfates

• Sulfides


Section 2 Identifying Minerals

Bellringer

Look at the mineral samples provided by your

teacher. List as many phrases as you can to describe

each sample. Organize these phrases into categories

to determine whether or not each sample is a different

mineral.

Record your response in your science journal.

Chapter 3


Section 2 Identifying MineralsChapter 3

• Identify seven ways to determine the identity

of minerals.

• Explain special properties of minerals.

Objectives



Identifying Minerals

• You can determine the identity of a mineral by

noting different properties.

• Color Minerals display a wide variety of colors,

and often the same mineral can be found in many

different colors.

• Because of this, color is usually not the best way

to identify a mineral.



Identifying Minerals, continued

• The way a mineral reflects light is called luster.

There are three types of mineral luster:

• Metallic

• Submetallic

• Nonmetallic



Identifying Minerals, continued

• The color of a mineral in powdered form is called

the mineral’s streak.

• A mineral’s streak can be found by running the

mineral against a piece of unglazed porcelain

called a streak plate.

• The color of a mineral’s streak is not always the

same as the color of the mineral sample.



Mineral Color, Luster, and Streak


Visual Concept

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Cleavage and Fracture

• Different types of minerals break in different ways.

• Cleavage is the tendency of some minerals to

break along smooth, flat surfaces.

• Fracture is the tendency of some minerals to

break unevenly along curved or irregular surfaces.



Hardness

• A mineral’s resistance to being scratched is called

hardness.

• To determine the hardness of minerals, scientists

use Mohs hardness scale, shown on the next slide.





Density

• Density is the measure of how much matter is

in a given amount of space. Density is a ratio of

an object’s mass to its volume.

• Different minerals have different densities.



Special Properties

• Some properties are particular to only a few types

of minerals.

• The properties shown on the next slide can help

you quickly identify some minerals.




Section 3 The Formation, Mining, and Use of

Minerals

Bellringer

Look at a mineral resource map of your state

and locate the mines closest to where you live.

Which mineral commodities are mined there?

Write your response in your science journal.

Chapter 3


Chapter 3

• Describe the environments in which minerals

forms.

• Compare the two types of mining.

• Describe two ways to reduce the effects of

mining.

• Describe different uses for metallic and

nonmetallic minerals.

Objectives


Minerals


Chapter 3

Formation of Minerals

• Minerals form in a variety of environments in the Earth’s crust. Each environment has a different set of physical and chemical conditions that determine the minerals’ properties.

• Evaporating Salt Water When a body of salt water dries up, minerals such as gypsum and halite are left behind.


Minerals


Chapter 3

Formation of Minerals, continued

• Metamorphic Rocks When changes in pressure, temperature, or chemical makeup alter a rock, metamorphism takes place.

• Minerals that form in metamorphic rock include calcite, garnet, graphite, hematite, magnetite, mica, and talc.


Minerals


Chapter 3


• Limestones Surface water and groundwater carry dissolved materials into lakes and seas, where they crystallized on the bottom.

• Minerals that form in this environment include calcite and dolomite.


Minerals


Chapter 3


• Hot-Water Solutions Groundwater works its way downward and is heated by magma, and then reacts with minerals to form a hot liquid solution.

• Dissolved metals and other elements crystallize out of the hot fluid to form new minerals, such as gold, copper, sulfur, pyrite, and galena.


Minerals


Chapter 3


• Pegmatites As magma rises upward from the Earth’s crust, it can form teardrop-shaped bodies called pegmatites.

• Many gemstones such as topaz and tourmaline, form in pegmatites.


Minerals


Chapter 3


• Plutons As magma rises upward through the crust, it sometimes stops moving before it reaches the surface and cools slowly, forming millions of mineral crystals.

• Eventually, the entire magma body solidifies, forming minerals such as mica, feldspar, magnetite, and quartz.


Minerals


Chapter 3

Mining

• Many kinds of rocks and minerals must be mined

to extract the valuable elements they contain.

• Geologists use the term ore to describe a mineral

deposit large enough and pure enough to be mined

for profit.

• Rocks and minerals are removed from the ground

by one of two methods.


Minerals


Chapter 3

Mining, continued

• Surface Mining When mineral deposits are

located at or near the surface of the Earth, surface-

mining methods are used to remove the minerals.

• Types of surface mines include open pits, surface

coal mines, and quarries.


Minerals


Chapter 3

Mining, continued

• Subsurface Mining methods are used when

mineral deposits are located too deep within the

Earth to be surface mined.

• Subsurface mining often requires that passageways

be dug into the Earth to reach the ore.


Minerals


Chapter 3

Responsible Mining

• Mining gives us the minerals we need, but it may

also create problems.

• Mining can destroy or disturb the habitats of plants

and animals.

• Waste products from a mine may get into water

sources, which pollutes surface water and ground

water.


Minerals


Chapter 3

Responsible Mining, continued

• One way to reduce the potential harmful effects

of mining is to return the land to its original state

after the mining is completed.

• Reclamation is the process by which land used

for mining is returned to its original state.

• Reducing our need for minerals by recycling is

another way to reduce the effects of mining.


Minerals


Chapter 3

The Use of Minerals

• Metallic Minerals are good conductors of heat

and electricity. They can be processed for various

uses, including building aircraft, automobiles, and

communications and electronic equipment.

• Examples of useful metallic minerals include gold,

silver, and copper.


Minerals


Chapter 3

The Use of Minerals, continued

• Nonmetallic Minerals are good insulators of

electricity. They have uses that range from glass-

making to producing computer chips.

• Calcite, one nonmetallic mineral, is a major

component of concrete, which is used in building

roads, buildings, bridges and other structures.


Minerals


Chapter 3

The Use of Minerals, continued

• Gemstones are highly valued for their beauty and

rarity, than for their usefulness.

• Important gemstones include diamond, sapphire,

ruby, emerald, aquamarine, topaz, and tourmaline.


Minerals


Minerals of the Earth’s Crust

Concept Mapping

Use the terms below to complete the concept map on

the next slide.

Chapter 3

gems

compounds

atoms

mineral ore

mining

minerals

diamonds


Minerals of the Earth’s CrustChapter 3


Minerals of the Earth’s CrustChapter 3

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