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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