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Halite crystal faces

Halite crystal faces. Each grain of table salt contains about 2 x 10 16 atoms of sodium, and the same number of chlorine atoms. Cleavage in halite. Cleavage in calcite. Minerals to know: Calcite --CaCO 3 in limestone and marble; gives off CO 2 (fizzes) in acid

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Halite crystal faces

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  1. Halite crystal faces

  2. Each grain of table salt contains about 2 x 1016 atoms of sodium, and the same number of chlorine atoms.

  3. Cleavage in halite

  4. Cleavage in calcite

  5. Minerals to know: Calcite--CaCO3 in limestone and marble; gives off CO2 (fizzes) in acid Halite-- NaCl--”rock salt”, evaporation of dense brine Gypsum--CaSO4 . H2O; scratch with fingernail; used in drywall Pyrite-- FeS2 “fool’s gold”; cubic crystals; main source of sulfur in acid rain, acid mine drainage. Quartz--SiO2; framework silicate, concoidal fracture, harder than glass Feldspar--most common mineral in earth’s crust; framework silicate, also contains sodium, potassium, calcium; harder than glass Mica--sheet silicate; perfect cleavage in one direction Olivine--isolated silicate; density varies with iron and magnesium content Clay--sheet silicate usually forming tiny crystals; key constituent of mudstone and many soils; may swell when wetted. And a non-mineral to know:Glass-- has no ordered crystal lattice (a chaos of ions); made by quenching a melt (no time to form lattice)

  6. iron magnesium

  7. Mineral: a naturally occurring, inorganic solid with a specific internal structure. It has a chemical composition that varies within certain limits and can be expressed by a chemical formula.

  8. The main reason that ocean crust is more dense than continental crust-- it has more iron-bearing minerals (like olivine).

  9. Olivine-rich beach sand from the Big Island of Hawaii. These grains weather out of basaltic lava flows.

  10. Hardness is directly related to the strength of the atomic bonds in the mineral.

  11. Apatite: Ca5(PO4)3(OH,F,Cl)

  12. Streak of hematite

  13. Pyrite FeS2“fools gold” has a black streak

  14. About 70 coal trains / day move thru Lincoln. All the full ones are going east. Why? Pyrite FeS2“fool’s gold” Pyrite forms in environments where iron and sulfur ions are present, and there is little oxygen. Peat bogs commonly contain pyrite. When pyrite is exposed to weathering or is burned, it generates sulfuric acid, and is the main cause of acid rain and acid mine drainage. Wyoming coal is low-sulfur (low-pyrite) coal

  15. This wetland was polluted by “acid mine drainage” (rainwater reacted with pyrite at a mine dump, making sulfuric acid). Acid mine drainage has taken a heavy toll on fish populations in the U.S.

  16. The Good News: wetlands are “sinks” for heavy metals Because other sulfide minerals besides pyrite form there (mercury, arsenic, selenium sulfides) they help to clean up polluted surface water.

  17. The Bad News: wetlands are “sinks” for heavy metals Because coal forms from peat deposited in wetlands, mercury, arsenic, and selenium are released when coal is burned.

  18. Silicate minerals

  19. Silicon-oxygen tetrahedron-- SiO4

  20. Silicon-oxygen tetrahedron-- SiO4

  21. What is the chemical formula for this mineral? SiO2 SiO4 SiO6 SiO8

  22. An “exploded” view of the minerals in granite

  23. Cleavage in mica

  24. Quartz is a framework silicate and has the chemical formula SiO2. It has no cleavage and breaks concoidally.

  25. Feldspar is the most abundant mineral in Earth’s crust, is a framework silicate with two perpendicular planes of cleavage. It also contains abundant sodium, calcium, and potassium ions. Pink grains and white grains are different varieties of feldspars; quartz looks blue (but is transparent).

  26. Asbestos is a commercial rather than a mineralogical term applied to a variety of fibrous silicate min- erals. Roofing and flooring materials, brake linings, and insulation commonly contain(ed) asbestos. Medical research has concluded that exposure to asbestos causes mesothelioma, asbestosis, and bronchial carcenoma. But which mineral is the bad actor?

  27. Asbestos is a commercial rather than a mineralogical term applied to a variety of fibrous silicate min- erals. Roofing and flooring materials, brake linings, and insulation commonly contain asbestos. Medical research has concluded that exposure to asbestos causes mesothelioma, asbestosis, and bronchial carcinoma. But which mineral is the bad actor?

  28. Asbestos is a commercial rather than a mineralogical term applied to a variety of fibrous silicate min- erals. Roofing and flooring materials, brake linings, and insulation commonly contain asbestos. Medical research has concluded that exposure to asbestos causes mesothelioma, asbestosis, and bronchial carcinoma. But which mineral is the bad actor? Chrysotile (the most abundant mineral used for asbestos) dissolves harmlessly in the body.

  29. Minerals can be identified with a polarizing microscope Tiny crystals of feldspar and olivine in basalt

  30. Swelling clays ~ $2Billion in damage to buildings & roads per year

  31. Minerals to know: Calcite--CaCO3 in limestone and marble; gives off CO2 (fizzes) in acid Halite-- NaCl--”rock salt”, evaporation of dense brine Gypsum--CaSO4 . H2O; scratch with fingernail; used in drywall Pyrite-- FeS2 “fool’s gold”; cubic crystals; main source of sulfur in acid rain, acid mine drainage. Quartz--SiO2; framework silicate, concoidal fracture, harder than glass Feldspar--most common mineral in earth’s crust; framework silicate, also contains sodium, potassium, calcium; harder than glass Mica--sheet silicate; perfect cleavage in one direction Olivine--isolated silicate; density varies with iron and magnesium content Clay--sheet silicate usually forming tiny crystals; key constituent of mudstone and many soils; may swell when wetted. And a non-mineral to know:Glass-- has no ordered crystal lattice (a chaos of ions); made by quenching a melt (no time to form lattice)

  32. Read chapter 4 “Igneous Rocks” 40

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