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Minerals

Minerals

What is a Mineral?

Naturally Occurring

Inorganic

Solid

Definite Chemical Formula

Definite Crystal Structure

Naturally Occurring

Formed by natural processes not in the laboratory

- Is an Ice Cube a mineral?

- Is the ice on the windshield of a car a

mineral?

Inorganic

Formed by inorganic processes; not living

Does not contain chains of carbon atoms

Solid

Not gas or liquid

-H2O as ice in a glacier is a mineral, but

water is not

Definite Crystal Structure

Highly ordered atomic arrangement of atoms in regular geometric patterns

8

Apatite Feldspar Diamond Quartz

Definite Chemical Formula

Minerals are expressed by a specific chemical formula

-Gold (Au)

-Calcite (CaCO3)

-Quartz (SiO2)

-Pyrite (FeS2)

Composition of the Earth’s Crust

Eight Elements that make up over 98% of Earth’s Crust

-Oxygen (O) -Silicon (SI) -Aluminum (Al) -Iron (Fe) -Calcium (Ca) -Sodium (Na) -Potassium (K) -Magnesium (Mg)

Where Do Minerals Come From?

Magma

Evaporation

How Are Minerals Identified?

Color

Luster

Hardness

Streak

Density

Crystal Shape

Cleavage and Fracture

Special Properties

Color

Usually the first and most easily observed

-Some minerals are always the same color

-Some minerals can have many colors

QUARTZ ROSE QUARTZ SMOKY QUARTZ

Luster

General appearance of a mineral surface in reflected light

Glassy-Obsidian

Hardness Resistance to scratching by different

items; “scratchability”

Mohs Hardness Scale >2 fingernail

3 penny

~5 Steel of a pocket knife

5.5 Window Glass

6.6 Steel of a file

7 quartz crystal

Mohs Mineral Hardness Scale

1) Talc

2) Gypsum

3) Calcite

4) Flourite

5) Apatite

6) Feldspar

7) Quartz

8) Topaz

9) Corundum

10) Diamond

Softest

Hardest

1

2

3

4

5

6

7

8

9

10

Streak

The color of a finely powdered mineral

Determined by rubbing the mineral on a piece of unglazed porcelain (streak plate)

Density

The amount of matter in a given space (Mass/Volume)

Crystal Shape

Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming

Cleavage and Fracture

Cleavage is the tendency of a mineral to split or crack along parallel or flat planes

Fracture occurs when a mineral breaks at random lines instead of at consistent cleavage planes.

BIOTITE QUARTZ Obsidian

No Cleavage 1 Direction of Cleavage Conchoidal Fracture

Special Properties

Magnetism (Magnetite)

Glowing under ultraviolet light (Fluorite)

Salty taste (Halite)

Smell (Sulfur)

Reaction to HCl (Calcite) Magnetite

Economic Importance of Minerals

Minerals are in many things we see and use everyday such as; bricks, glass, cement, plaster, iron, gold

Every American Requires 40,000 Pounds of New Minerals per Year

at this level of consumption the average newborn infant will need a lifetime supply of:

-795 lbs of lead (car batteries, electric components) -757 lbs of zinc (to make brass, rubber, paints) -1500lbs of copper (electrical motors, wirings -3593 lbs aluminum (soda cans, aircraft) -32,700 lbs of iron (kitchen utensils, automobiles,

buildings) -28,213 lbs of salt (cooking, detergents) -1,238,101 lbs of stone, sand, gravel, cement (roads,

homes, etc.)