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Chapter 13

Minerals of the Earth's Crust

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Vocabulary:

Mineral Luster Ore

Element Streak Reclamation

Compound Cleavage

Crystal Fracture

Silicate mineral Hardness

Nonsilicate Density

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Section 1 What is a Mineral?

Mineral- is a naturally formed, inorganic solid that had defiant crystalline structure.

How to know if something is a mineral:

1) Has to be nonliving.2) Has to be solid.3) Has crystalline structure.4) Must be nature made.

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Minerals are made from elements or groups of elements.

Element- a substance that cannot be separated or broken down into a simpler substance by chemical means. (single Lego block)

Compound- a substance made up of atoms of two or more different elements joined by chemical bonds. (lots of legos)

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Crystals

Crystals- a solid whose atoms, ions, or molecules are arranged in a definite pattern.

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Two GROUPS of Minerals

Silicates- a mineral that contains a combination of silicon, oxygen, and one or more element.

Silicates make up 90% of the Earth’s crust.

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Two GROUPS of Minerals

Non- Silicates- a mineral compound that does NOT contain compounds of silicon and oxygen.

Non-silicates can contain oxygen and other elements but do not contain silicon.

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Section 2 Identifying Minerals

Geologists use several ways to identify minerals.

We will learn the 7 most common ways to identify minerals by their characteristics.

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1. Color

We can identify minerals by color. This is not a real good way because air, water, and impurities can affect color.

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2. Luster Luster- is the way a surface reflects light.

Shiny minerals usually have a metallic luster.

Dull minerals usually have a nonmetallic luster.

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3. Streak

Streak-The color of the powder of a mineral.The streak can be found by rubbing a mineral on a streak plate.

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4. Cleavage and FractureCleavage- the splitting of a mineral along smooth,

flat surfaces.

Fracture- the manner in which a mineral breaks along either curved or irregular surfaces.

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5. Hardness

Hardness- the measure of the ability of a mineral to resist scratching.

Mohs Hardness Scale ranks mineral’s hardness from 1 (soft) to 10 (hard).

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6. Density

Density- the ratio of the mass of a substance to the volume of a substance.

Specific Gravity is the ratio of the mineral’s density to the density of water.

Ex. Water has a density of 1 g/cm3. Gold has a density of 19 g/cm3. To get gold’s Specific Gravity SIMPLY DROP THE UNITS!Gold’s Specific Gravity is 19.

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7. Special PropertiesSome minerals can be identified by special properties

such as:

Fluorescence - Glow under a black light.

Chemical Reaction - Some minerals will “Fizz” when you put acid on them.

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7. Special Properties

Optical Properties - some minerals will act like a magnifying glass.

Magnetism - Some minerals are magnetic.

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7. Special Properties

Taste- Some minerals will taste salty.

Radioactivity- Some minerals are RADIOACTIVE!!

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Section 3 The Formation, Mining, and Use of Minerals

What we will learn in this section:1. Describe the environments in which minerals

will form.2. Compare the two types of mining.3. Describe two ways to reduce the effects of

mining.4. Describe different uses for metallic and non-

metallic minerals.

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MiningMining is the process of getting ore out of the

ground.

Ore— a natural material whose concentration of economically valuable mineral is high enough for the material to be mined profitably.

Mining can be done inside the earth and on the surface.

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Types of Surface Mining

1) Surface Mining—where minerals are dug up close to the surface of the Earth.

Types of surface mining include:• Open Pit Mining—used to remove large, near-surface

deposits of economically important minerals. Ex. gold, copper.

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• Quarry—open pits used to mine building stone, crushed rock, sand and gravel.

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• Surface Strip Mining— coal is removed in strips.

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Underground Mining

2. Subsurface Mining—minerals deep in the Earth are dug out using horizontal passage ways or a vertical shafts.

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Effects of Mining

• Mining gives us mineral we need, but it creates problems.

• Reclamation—process of returning land to its original condition after mining is complete.

• Reclamation has been required by law since the 1970s.

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The Uses of Minerals

• Metallic Minerals- are good conductors of heat and electricity.

• Used in airplanes, cars, computers, and other electronic devices.

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The Uses of Minerals

• Non-Metallic Minerals- are good insulators of electricity and building products.

• Used in concrete, drywall, toothpaste, glassmaking, etc.

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The Uses of Minerals

• Gemstones are highly valued for their beauty and rarity rather than their usefulness.

• Used in rings, necklaces, bracelets, and other jewelry.