Warm Up How does the sun play a part in the rock cycle? How does gravity play a part in the rock cycle? How does plate tectonics play a part in the rock cycle?

Minerals About 3000 minerals are found in the earth’s crust.

Why are minerals important? 1.They form rocks, which make up Earth’s surface. 2. They have shaped human civilization: - gold & silver - iron - calcite (makes up limestone and marble)

Definition of a Mineral Minerals 1. Naturally occurring 3. Solid substance 4. Orderly crystalline structure 5. Specific chemical composition 2. Inorganic

Naturally Occurring Formed by natural processes, not by scientists in a lab. Cubic zirconia, made in a lab…. Shiny, but NOT a mineral! Diamond, formed by natural processes… MINERAL!

Inorganic Is not alive and has never been alive in it’s existence Is salt a mineral? What about sugar?Or coal?

Solid Solids have definite shapes and volumes –Liquids and gases do not! Liquids and gases cannot be classified as minerals.

Crystalline Structure Crystal - The atoms of minerals are arranged in regular, repeating geometric patterns Sapphire crystalline structure

Well-formed crystals are rare! Most crystals don’t have room to grow to be well formed. Rocks are made of mineral crystals growing into each other. Crystal shapes aren’t always easy to observe because the crystals form in limited spaces. Quartz Granite

Cooling Speed Determines Crystal Structure Pegmatite (huge crystals) Obsidian Coarse Grained Granite Andesite

Specific Chemical Compositions Each type of mineral has a chemical composition that is unique to that mineral. Graphite = Carbon (C) Gold (Au) Zinc (Zn) Rutile (TiO 2 ) Soda Ash (Na 2 CO 3 )

1. Crystallization from magma 2. Precipitation 3. Pressure and temperature 4. Hydrothermal solutions How Minerals Form

2. Carbonates 3. Oxides Types of Minerals (Families) 4. Sulfates and Sulfides 5. Evaporite Minerals and Halides 6. Native elements 1. Silicates

Silicates 90% minerals on Earth ( Most common) Si, O, and 1 or more metallic ions in Tetrahedron shape Benitoite (BaTiSi 3 O 9 ) Eudialyte Na 15 Ca 6 Fe 3 Zr 3 Si(Si 25 O 73 )(O, OH,H 2 O) 3 (Cl,OH) 22

Carbonates Malachite Cu 2 (CO 3 )(OH) 2 Aragonite (CaCO 3 ) Dolomite, CaMg(CO 3 ) 2 Cerussite (PbCO 3 ) Calcite (CaCO 3 ) Minerals that contain the elements carbon, oxygen, and one or more other metallic elements Rhodochrosite (MnCO 3 )

Oxides Minerals that contain oxygen and one or more other elements, which are usually metals Pyrolusite dendrites (MnO 2 ) Corundum (Al 2 O) AKA Rubies! Hematite (Fe 2 O 3 ) Magnetite (Fe 3 O 4 ) Rutile (TiO 2 ) Cuprite (Cu 2 O)

Sulfates and Sulfides Minerals that contain the element sulfur Gypsum (CaSO 4 ·2H 2 O) Alunite Al 3 (SO 4 ) 2 (OH) 6 Anhydrite (CaSO 4 ) Cinnabar (HgS) Galena (PbS)Pyrite (FeS 2 )

Evaporite Minerals and Halides Borax, Na 2 B 4 O 5 (OH) 4 ·8H 2 O Fluorite (CaF 2 ) Halite (NaCl) Evaporite minerals are those that form by coming out of solution when seawater and the waters of large lakes evaporate. Halides are chemical compounds that involve the halogen (salt- forming) elements fluorine and chlorine. Ulexite (NaCaB 5 O 6 (OH) 6 ∙5H 2 O) Gypsum (CaSO 4 ·2H 2 O) (a sulfate and an evaporite) Sylvite (KCl)

Native Elements Minerals that exist in relatively pure form Graphite is native carbon (C) Copper (Cu) Iron, the element Fe, is almost always found on Earth in meteorites Diamond is native carbon, (C) Gold, the element Au Platinum, the element Pt

Identifying Minerals Over 200 known Can be identified from physical properties How can I tell what this is?

Identification Properties COLOR –Least useful –Many have similar colors –Other elements may change color –Beryl (emerald) 

Colors of Quartz

Identification Properties LUSTER –The shine in reflected light LUSTER TERMDESCRIPTION adamantinevery brilliant - as in diamond resinous looks like resin or hardened tree sap vitreous glassy, but not as shiny as diamond metalliclooks like metal silkyhas a smooth and fibrous sheen pearlysmooth and iridescent greasylooks like it's coated with oil earthylooks like dirt

LUSTER Glassy Adamantine Greasy Metallic

Identification Properties CRYSTAL SHAPE –Hard to find –Must have room to grow –Crystal Systems Cubic Orthorhombic Tetragonal Triclinic Hexagonal Monoclinic

CRYSTAL SHAPE

Quartz Often Exhibits Good Crystal Form.

Identification Properties STREAK –Color of its powder –Does not change –Metallic: as dark as sample –Nonmetallic: white to colorless Streak Plate ↑

Identification Properties CLEAVAGE –Tendency to split easily or break along flat surfaces –Mica – 1 direction FRACTURE –Break on uneven surfaces –Conchoidal - obsidian

Identification Properties HARDNESS –Resistance to being scratched –Mohs’ Scale of Hardness

Mohs’ Scale of Hardness 1 - Talc – fingernail scratches it easily 2 - Gypsum – fingernail scratches it 3 - Calcite – copper penny just scratches it 4 - Fluorite – steel knife scratches it easily 5 – Apatite – steel knife scratches it 6 – Feldspar – steel knife does not scratch it easily; it scratches window glass 7 – Quartz – hardest common mineral; it scratches steel and hard glass easily 8 – Topaz – harder than any common mineral 9 – Corundum – it scratches topaz 10 – Diamond – hardest of all minerals

Special Identification Properties Fluorescence

Special Identification Properties Magnetism Magnetite

Special Identification Properties Taste This will quickly identify the mineral halite (salt). If you are new to this process you must use this one with caution, as you never know what the unknown may be. Often, you may need to resort to this method (until you more fully understand other identifying traits) to differentiate halite from calcite. If you do taste the sample (especially in a class environment) you should realize that it has been handled by and probably tasted by hundreds of others.