Mineral Formation

Methods of Formation

Crystals may form from magma cooling Cools slow = large crystals Cools quickly = small crystals Confined space = small crystals Open space = large crystals

Crystals may form out of solution. As liquid evaporates, mineral is left behind Ex/ “Bad Koolaide”, sea salt on skin

Silicates

Structure of all silicates is a Tetrahedron

1 Silicon & 4 Oxygen arranged in a pyramid structure

96% of minerals are known as silicates.

Oxygen nearly 50% of the Earth’s crust. Silicon makes up over 27%

Carbonates & Oxides

Carbonates

Metal + carbonate CO3

Fizz in the presence of HCl acid

Ex/ marble, limestone, & calcite

Oxides

Metal + oxygen

Good sources of iron

Ex/ Magnetite & Hematite

Other Mineral Groups

Sulfides = sulfur + another element (Pyrite)

Sulfates = sulfate (SO4) + another element

Halides = Cl or F (fluorine) bonded with a calcium, sodium or potassium

Native elements = made of one element only (Gold, Silver, Sulfur, etc.)

Mineral Use Categories

Remember that minerals make up the entire crust Making up rocks On their own

Many are used for economic reasons

2 economic categories Ore minerals Gems

Ore Minerals

Ore: mineral found with in deposits that can be profitably mined

This means that the money earned from the ore itself outweighs the cost of extracting it

Most ores are found as compoundsWhile many precious metals are native

Ore Examples

Chalcopyrite: mined for Copper

Galena: mined for Lead

Sphalerite: mined for Zinc

Halite: mined for table salt

Gypsum: Sheet rock (dry wall) & plaster

Hematite: source of Iron

Bauxite: source of Aluminum

Gems

Gems are valuable for their beauty rather than their industrial uses Precious Semi-precious

The rarer the gem, the more valuableEmeralds & Rubies are actually more valuable than

diamonds

Trace elements can make an ordinary mineral more prized Ex/ Amethyst: form of quartz; trace elements make it purple

More on Gems

PreciousDiamonds

Emeralds

Rubies

Sapphires

Opals

Semi-preciousAmethystJasperAgateTiger EyeSometimes Turquoise Topaz Garnet