Conversations with the Earth Tom Burbine [e-mail]

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Conversations with the EarthTom
Burbinetburbine_at_framingham.edu
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Mineral

• A naturally occurring, homogeneous inorganic
  solid substance having a definite chemical
  composition and characteristic crystal structure
• 4,000 known minerals
• Of these, perhaps 100 can be called "common"
• 50 are "occasional
• rest are "rare" to "extremely rare".

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• Earth is made of minerals

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• Can you name any minerals?

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• Quartz SiO2
• Diamond C
• Graphite C
• Calcite CaCO3
• Talc - Mg3Si4O10(OH)2

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Is ice a mineral?
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Is ice a mineral?

• Yes, as long as it was made inorganically

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Crystal Structure

• Crystalline structure - orderly three-dimensional
  arrangement of atoms or molecules
• Forms crystals

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Color

• Usually the most noticeable property
• Sometimes minerals can have a wide variety of
  colors

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Clarity

• Transparent clear
• Translucent foggy
• Opaque light doesnt travel through

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Crystal Form

• Perfectly grown crystals can have a perfect
  crystal form (e.g., cube, pyramid, prism)

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Luster

• How light reflects from a mineral
• Metallic luster reflects like a metal
• Nonmetallic luster doesnt reflect like a metal
• Vitreous like a glossy photograph
• Waxy like the luster of a candle
• Satiny like the luster of satin
• Earthy like dry soil
• Greasy like the luster of grease
• Porcelaneous like the luster of porcelain

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Streak

• Color of a substance as a fine powder
• A mineral is scratched on a streak plate

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Hardness

• Mohs Hardness scale
• 1-10 scale
• Hard minerals-
• can scratch glass
• Soft minerals
• cant scratch glass

Streak Plate
Penny
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Cleavage

• Cleavage tendency of some minerals to break
  along flat, parallel surfaces
• Cleavage planes are parallel surfaces of weak
  chemical bonding
• Fracture is a break in a mineral does not occur
  along a cleavage plane

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Tenacity

• Tenacity - resists breakage
• Brittle shatters like glass
• Malleable like clay
• Elastic like a plastic comb
• Sectile carved with a knife

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Reaction with acid

• Fizzes with cool, dilute hydrochloric acid
• Carbonate minerals (minerals with CO3)
• Calcite readily fizzes
• Dolomite will only fizz if powdered

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Striations

• Straight, hairline grooves on the cleavage
  surfaces
• Plagioclase feldspar has striations

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Magnetism

• Magnetic
• Magnetite is magnetic

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Specific gravity

• Density of a substance divided by the density of
  water
• e.g., quartz has a specific gravity of 2.65

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Any Questions?