Conversations with the Earth Tom Burbine [e-mail]

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Conversations with the EarthTom
Burbinetburbine_at_framingham.edu
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Quiz on Thursday

• You can bring in your hand-written mineral sheets

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• Cation positively charged ion
• Anion negatively charged ion
• NaCl Na is the cation and Cl- is the anion

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Mineral classes that we studied

• Silicates contain silicon and oxygen
• Carbonates contain (CO3)2-
• Sulfates contain (SO4)2-
• Halites contain F-, Cl-, Br-, or I- as an anion
• Oxides - contain oxygen (O2-) that is bonded to
  one or more metal ions
• Sulfides - contain sulfur (S2-) as the anion
• Native elements

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Graphite

• C
• Used in pencils
• Greasy feel
• Grey streak
• Electrical conductor

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Olivine

• (Mg,Fe)2SiO4
• Green, no cleavage
• Olivine and high pressure structural
  variants make up over 50 of the
  Earth's upper mantle

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Biotite

• K(Mg,Fe)3AlSi3O10(F,OH)2
• Sheets
• Dark color

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Galena

• PbS
• Cubes
• Gray streak
• Lead ore

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Pyrite

• FeS2
• Hardness 6 to 6.5
• Gray streak
• Can form cubes
• Ore for sulfur

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Hematite

• Fe2O3
• Reddish streak
• Metallic or non-metallic luster

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Fluorite

• CaF2
• Hardness of 4
• Colorless, purple, green, yellow

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Halite

• NaCl
• Salt
• Cubes
• Results from the drying up of
  lake beds or seas

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Muscovite

• KAl2(AlSi3O10)(F,OH)
• Comes in sheets
• Clear

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Talc

• Mg3Si4O10(OH)2
• In loose form, it is known as
  talcum powder
• Most tailor's chalk is talc

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Amphibole

• Ca2(Mg,Fe,Al)5(Al,Si)8O22(OH)2
• Prisms with cleavage at
  56o and 124o
• Fibrous varieties used as
  fireproof clothing

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Calcite

• CaCO3
• Single calcite crystals display an
  optical property
  called
  double refraction

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Garnet

• Mg3Al2(SiO4)3
• Hardness of 7
• Forms dodecahedrons
• Gemstone

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Gypsum

• CaSO42H2O
• Hardness of 2
• Colorless, white,
  or gray

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Dolomite

• CaMg(CO3)2
• Fizzes in dilute HCl
  if powdered

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Quartz

• SiO2
• second most abundant mineral in the
  Earth's continental crust

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Chalcopyrite

• CuFeS2
• Hardness of 3.5-4
• Dark gray streak
• source of ignition in early
  firearms

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Chlorite

• (Mg,Fe)3(Si,Al)4O10
• Very soft
• The powder generated by
  scratching is green.
• Feels oily when rubbed
  between the fingers.

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Sphalerite

• (Zn,Fe)S
• Smells like rotten eggs if
  scratched/powdered
• Ore of zinc

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Plagioclase feldspar

• CaAl2Si2O8
• Has striations

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Magnetite

• Fe3O4
• most magnetic of all the
  naturally occurring minerals on Earth

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Augite (pyroxene)

• (Ca,Na)(Mg,Fe,Al)(Si,Al)2O6
• Cleavages at nearly right
  angles

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Potassium feldspar (Orthoclase)

• KAlSi3O8
• Usually pinkish

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Kaolinite

• Al2Si2O5(OH)4
• soft, earthy, usually white
  mineral
• Produced by weathering of
  feldspars
• main component in porcelain

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Any Questions?