What is a mineral?

• Solid• Forms naturally• Not formed by living things• Has a crystal shape• Has a chemical composition

What are minerals made of?

• Elements and Compounds• 8 elements make up 98.5% of the crust.• Two most abundant elements• Oxygen and Silicon• Native elements – made of 1 element

Eight most common elements• 46.6% Oxygen (O)• 27.7% Silicon (Si)• 8.1% Aluminum (Al)• 5.0% Iron (Fe)• 3.6% Calcium (Ca)• 2.8% Sodium (Na)• 2.6% Potassium (K)• 2.1% Magnesium (Mg)

How minerals form

• Forms from molten material from the Earth.– Cooling determines grain size.

• Forms through evaporation process– Halite – Salt

• Other minerals can be changed into different minerals by:– Heat– Pressure– Chemical action

Nonsilicate Mineral Groups

• Oxides – elements with oxygen.• Sulfides – elements with sulfur.• Halites – elements combine with chlorine,

iodine, bromine, or fluorine.• Carbonates – compounds with carbon and

oxygen.• Sulfates – compounds with sulfur and oxygen.

Mineral Uses

• Usually not the mineral itself, but the ore of the elements in the mineral contains the value.

• Ore – minerals from which useful material can be extracted at a profit.

• Mineral not used for profit called gangue.

Physical Properties• Color – first and most easily observed, least

useful• Crystal shape – arrangement of atoms that

form a mineral• Streak – color of a mineral’s powder • Cleavage – mineral that breaks on a flat

surface.• Fracture – mineral that breaks on an uneven

(jagged) surface.

Physical Properties (cont.)

• Acid Test – mineral reacts to HCl (hydrochloric acid) indicates that it is a carbonate – made of carbon and oxygen

• Hardness – measure of how easy a mineral can be scratched. Scale 1-10– Talc=1– Diamond=10

• Specific Gravity – ratio of the weight of a mineral to the equal weight of an equal volume of water.

Other special properties

• Magnetism• Fluorescence – glow under a UV light.• Phosphorescence – will continue to glow after

the lights are off.• Double Refraction – bending of light rays,

produces a double image.

Uses of minerals

• Gems – are highly prized minerals like diamond, rubies, opals, topaz, and other birth stones.

• Ores – a useful substance mined for a profit– Bauxite – ore of aluminum

Galena

Pyrite

Calcite

Halite

Gypsum

Magnetite

Feldspar

Sulfur

Muscovite

Muscovite