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!