Minerals GEO-111

Requirements for a mineral

Naturally occurring
• Formed by geologic processes
• Solid
• Crystalline structure
• Definable chemical composition
•Inorganic

Mineral Physical Properties

• Color and streak
• Luster
• Density
• Hardness
• Manner of breakage
• Special properties
- Reaction with acid
- Magnetism
- Taste and smell

mineral color

Not a definitive property
- Streak color of residue left on plate

Bonding controls

hardness, scratching breaks bonds

Mineral hardness is measures on

Mohs hardness scale

Mineral cleavage

Manner of breakage
- uniform

- Fracture

breakage along irregular, not flat planes, crystals

density is influenced by

atomic packing

Arrangement of atoms

crystal-form and cleavage

cations

positively charged ions

anion

A negatively charged ion

ionic bonding

attraction between ions of opposite charge

covalent bonding

electrons are shared

Metallic bonding

electrons move freely among many atoms

Van der Waals force

weak charged field due to uneven arrangement of electrons

Transmission electron microscope (TEM)

A microscope that uses an electron beam to study the internal structure of thinly sectioned specimens.

Silicate minerals

95% of continental crust
- Almost 100% of oceanic crust and mantle

Native Elements

Pure masses of a single element• Examples:- Gold - Au- Copper - Cu

Gem

finished stone ready to be set

Precious stone

rare and expensive- Diamond, ruby, sapphire, emerald