ROCK vs. MINERAL n ROCK n Mixture n Can be separated by physical means n MINERAL n Pure substance n...
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Transcript of ROCK vs. MINERAL n ROCK n Mixture n Can be separated by physical means n MINERAL n Pure substance n...
ROCK vs. MINERAL
ROCK Mixture Can be
separated by physical means
MINERAL Pure
substance Has specific
formula Cannot be
separated by physical means
FROM A MELT
Form from lava or magma
most common method
Usually forms large crystals
example: quartz, gemstones
From a solution
Evaporation Halite, gypsum
Usually soft minerals
Precipitation from saturated solution Calcite, barite
From Hydrothermal
Hot watery solutions Rain water
percolates and is heated by interior of earth
Chrysocolla, azurite, gold
Classification of Minerals
Nearly 4000 minerals have been identified on Earth
Only 8 elements that make up over 98% of the Earth’s crust- THE BIG 8
ABUNDANCE OF ELEMENTS
ELEMENT % BY WEIGHT
OXYGEN 46.6%
SILICON 27.7%
ALUMINUM 8.1%
IRON 5.0%
CALCIUM 3.6%
SODIUM 2.8%
POTASSIUM 2.6%
MAGNESIUM 2.1%
The silicate (SiO4)-4 molecule (tetrahedron)
Wants to join with positive ions Fe, Mg, K, Na, Al, Ca
Or joins with other tetrahedron (covalent) Si joins tough with O = hard minerals (mostly)
Positive ions may substitute for each other If same charge and same size
Ca and K Fe and Mg
Use commas in formula to indicate substitution
olivine
NON-SILICATES
Carbonates (CO3) Calcite, dolomite
Sulfates (SO4) gypsum
Halides (halogens) fluorite
Native minerals elements