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