Minerals: Properties and Uses

A Mineral is Naturally occurring Naturally occurring Inorganic (not made from animals or plants) Inorganic (not made from animals or plants) Solid Solid with a definite chemical composition (formula) with a definite chemical composition (formula) and an orderly arrangement of atoms (crystal structure) and an orderly arrangement of atoms (crystal structure)

Crystal Structure

What determines the use or uses of a particular mineral? Use is determined by Use is determined by physical properties physical properties chemical composition chemical composition

What are physical properties? Color Color Luster Luster –Metallic –Nonmetallic Streak Streak –Color of the powdered mineral Hardness Hardness –Moh’s Scale from 1-10 Breakage Breakage –Cleavage –Fracture

Physical Properties Unique combinations for each mineral Unique combinations for each mineral Useful for Identification Useful for Identification Determine some uses Determine some uses

Use determined by physical properties Chemical composition is of little concern. Chemical composition is of little concern. Specific physical properties are the basis for use. Specific physical properties are the basis for use. Examples: 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 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. 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 Gold – jewelry, dentistry, electronics

Examples of minerals used for their chemical composition Hematite, magnetite, limonite – iron and steel Hematite, magnetite, limonite – iron and steel

Examples of minerals used for their chemical composition Malachite, azurite, chrysocolla – copper: wires, pennies, electronics Malachite, azurite, chrysocolla – copper: wires, pennies, electronics

Examples of minerals used for their chemical composition Gold – jewelry, dentistry, electronics Gold – jewelry, dentistry, electronics Hematite, magnetite, limonite – iron and steel Hematite, magnetite, limonite – iron and steel Malachite, azurite, chrysocolla – copper: wires, pennies, electronics Malachite, azurite, chrysocolla – copper: wires, pennies, electronics Galena – lead, formerly plumbing and paints, now – mostly chemicals industry Galena – lead, formerly plumbing and paints, now – mostly chemicals industry Bauxite – aluminum: cans, foil, bikes, aircraft, etc. Bauxite – aluminum: cans, foil, bikes, aircraft, etc.

Abundance of chemical elements in Earth’s Crust O – 46.6%Si – 27.7% O – 46.6%Si – 27.7% Al – 8.1%Fe – 5.0% Al – 8.1%Fe – 5.0% Ca – 3.6%Na – 2.8% Ca – 3.6%Na – 2.8% K – 2.6%Mg – 2.1% K – 2.6%Mg – 2.1% Other – 1.7% Other – 1.7%

Other Chemical Elements 1.7% of crust 1.7% of crust Highly useful Highly useful Highly valuable Highly valuable Example: Copper – average crustal abundance is 50 ppm, but the US alone uses 2 million tons per year! Example: Copper – average crustal abundance is 50 ppm, but the US alone uses 2 million tons per year!