MINERALS

ReeseMINERALSHow do they formMinerals form when molten materials cools and hardens inside the Earth or on the surface.Sometimes minerals from when solutions with solutes evaporate.MINERALSOccur naturally and are inorganic solids (not alive).

Have crystalline structure.

MINERALSChemically minerals are elements or compounds.Example: Gold is an element & a mineral.Example: NaCl is a compound & a mineral.

MINERALSRocks are made up of two or more minerals.Example: Limestone is a rock made up minerals calcite & aragonite. Rocks can be minerals but not all minerals are rocks.Example: Cu is a mineral but is not a rock

MINERALSThere are about 3,000 minerals on Earth.

BARITE

CARBON

QUARTZ

GRAPHITE

Copper

FLUORITE

MINERAL PROPERTIESLUSTERThe way a minerals surface reflects light.

LUSTERMay vary from one sample to another sample of the same substance. Two major types of luster:Metallic Nonmetallic

Metallic Luster

Nonmetallic lusterEarthy Luster

Glassy

Nonmetallic Pearly Luster

COLORNot very useful for identifying minerals whose color vary with the sample.Example: the colors of minerals quartz & fluorite vary with their samples. Quartz Fluorite

COLORUseful only for those minerals which always have the same color or very unique colors.Example: Malachite green azurite----- blue

SULFUR

Malachite

Azurite

STREAKColor of a mineral in it powdered form.Can be obtained by rubbing the mineral across a streak plate-- a piece of unglazed porcelain tile.Example: hematite always gives a reddish brown streak no matter what type of luster it displays.

Streak ExamplesHematite leaves a reddish brown streak.

Streak ExamplesPyrite leaves a greenish black streak.

HARDNESSAbility of a mineral to resist scratching.It is tested using the Mohs Hardness Scale.

Mohs Hardness ScaleBased on the fact that a harder mineral will scratch a softer one.Ten minerals are numbered from softest to hardest.Talc is the softest & has a value of 1.Diamond, the hardest of all minerals, has a value of 10.

DENSITYUseful mineral identification property.Used to determine the identity and purity of minerals.Pure mineral density is a constant value.Density = mass/volume.Example: gold and pyrite appear similar. Pyrite is often called fools gold. You can tell the two minerals apart by comparing their densities.Golds density: 19.3 g/ccPyrites density: 5.01 g/cc