minerals of the earth chapter 3. minerals of the earth’s crust section 1 what is a mineral?...

MINERALS OF THE EARTHChapter 3

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

Table of Contents

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?


Mineral Structure, continued• 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.

You may stop the video at any time by pressing the Esc key.

Visual Concept


Mineral Structure, continued• 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


Mineral Structure, continued• A mineral that is composed of only one element is called a native element.

• Gold and silver are examples of native elements.


Mineral Structure, continued• 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 1 What Is a Mineral?

BellringerCompare the piece of graphite (used in 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 Interactive notebook.

Chapter 3

Graphite and Diamond

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


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 2 Identifying Minerals

BellringerLook 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 interactive notebook.

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

Section 3 Formation, Mining, & Use of 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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.


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.



BellringerLook 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

Minerals of the Earth’s Crust

Concept MapUse the terms below to complete the concept map on the next slide.

Chapter 3

gemscompoundsatomsmineral ore

miningmineralsdiamonds

Minerals of the Earth’s CrustChapter 3

End of Chapter 3 Show

minerals of the earth chapter 3. minerals of the earth’s crust section 1 what is a mineral?...

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