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!