Minerals: Properties and Uses

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Minerals: Properties and Uses

A Mineral is

 Naturally occurring

 Inorganic (not made from animals or plants)

 Solid

 with a definite chemical composition

(formula)

 and an orderly arrangement of atoms

(crystal structure)

Crystal Structure

What determines the use or uses of a particular mineral?

 Use is determined by

 physical properties

 chemical composition

What are physical properties?

Color

 Luster

– Metallic

– Nonmetallic

 Streak

– Color of the powdered mineral

 Hardness

– Moh’s Scale from 1-10

 Breakage

– Cleavage

– Fracture

Physical Properties

 Unique combinations for each mineral

 Useful for Identification

Determine some uses

Use determined by physical properties

 Chemical composition is of little concern.

 Specific physical properties are the basis for use.

 Examples:

– Quartz for its hardness: sand paper

– Talc for its absorbency: baby powder

– Graphite for its softness: pencil “leads”

– Halite for its taste

Graphite

Talc

Some minerals are used for their chemical composition

 Physical properties are of little concern

 Chemical composition is important because certain minerals are sources of valuable chemical elements or are of use by themselves.

Examples of minerals used for their chemical composition

 Gold – jewelry, dentistry, electronics

Examples of minerals used for their chemical composition

 Hematite, magnetite, limonite – iron and steel

Examples of minerals used for their chemical composition

 Malachite, azurite, chrysocolla – copper: wires, pennies, electronics

Examples of minerals used for their chemical composition

Gold – jewelry, dentistry, electronics

 Hematite, magnetite, limonite – iron and steel

 Malachite, azurite, chrysocolla – copper: wires, pennies, electronics

 Galena – lead, formerly plumbing and paints, now – mostly chemicals industry

Bauxite – aluminum: cans, foil, bikes, aircraft, etc.

Abundance of chemical elements in Earth’s Crust

 O – 46.6%

 Al – 8.1%

Ca – 3.6%

K – 2.6%

 Other – 1.7%

Si – 27.7%

Fe – 5.0%

Na – 2.8%

Mg – 2.1%

Other Chemical Elements

 1.7% of crust

 Highly useful

Highly valuable

Example: Copper – average crustal abundance is 50 ppm, but the US alone uses

2 million tons per year!

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