Minerals

Background Information  Element: a substance made up of only one kind of atom Example: Gold (Au), Aluminum (Al) As of 2011, there are 118 elements, 90 are naturally occurring. As of 2011, there are 118 elements, 90 are naturally occurring. Compound: a mixture of two or more elements Example: Salt (NaCl) Sodium and Chlorine

What is a Mineral? 1.Naturally occuring 2.Inorganic—Not Living 3.Solid 4.Crystal Structure 5.Definite Chemical Composition

Minerals can form two ways 1. Magma and Lava Minerals form as hot magma cools inside the crust, or as lava hardens on the surface.Minerals form as hot magma cools inside the crust, or as lava hardens on the surface. When these liquids cool to a solid state, they form crystals.When these liquids cool to a solid state, they form crystals.

2.Solutions  Solution is a mixture in which one substance is dissolved in another.  When elements and compounds that are dissolved in water leave a solution, crystallization occurs.

Some minerals form when solutions evaporate. Example: Death Valley

Identifying a Mineral Each mineral has characteristic properties that can be used to identify it.Each mineral has characteristic properties that can be used to identify it.

Color  Color of a mineral is an easily observed physical property.  Light or Dark? Halitehematite

Streak  The mineral is rubbed against a piece of unglazed porcelain tile.  Sometimes the streak color and the mineral color are different.  Ex: gold-gold pyrite-greenish black

Luster  Luster is how a mineral reflects light.  Metallic  Nonmetallic—includes glassy, earthy, waxy and pearly. GalenaQuartz

Density  Each mineral has a characteristic density.  Density = mass/volume

Hardness1Softest Ex. Talc Fingernail 2 Ex. Gypsum fingernail 3 Ex. Calcite Penny 4 Ex. Flourite Steel knife 5 Ex. Apatite Steel knife can scratch it 6 Ex. Feldspar It can scratch glass 7 Ex. Quartz Steel & hard glass 8 Ex. Topaz Can scratch quartz 9 Ex. Corundum Can scratch topaz 10Hardest Ex. Diamond Will scratch all other substances

Cleavage  A mineral that splits easily along flat surfaces.

Fracture  Fracture is when a mineral breaks in an irregular way.

Crystal Structure  Each mineral grows atom by atom to form a particular crystal structure  Two main types  Cubic--Halite  Hexagonal--Quartz