Minerals

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Minerals

• Unit 3 Notes

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What is a mineral?

• A mineral must be all of the following
• Naturally occurring
• Inorganic solid (not living)
• Definite structure
• Definite composition (what its made of)

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What is a crystal?

• A crystal is a solid in which the atoms are
  arranged in repeating patterns

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Crystal Structure

• Here are the six crystal systems that all
  minerals belong to
• Cubic sylvite, halite
• Hexagonal emerald, graphite
• Tetragonal wulfenite, zircon
• Orthorhombic topaz, sulfur
• Monoclinic gypsum, mica
• Triclinic kyanite, turquoise

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Elements in Earths Crust
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Name Symbol By Mass
Oxygen O 46.6
Silicon Si 27.7
Aluminum Al 8.1
Iron Fe 5.0
Calcium Ca 3.6
Sodium Na 2.8
Potassium K 2.6
Magnesium Mg 2.1
Others ---- 1.5
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Mineral Composition

• Silicates (Si O)
• Carbonates (C O)

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Silicates
The silica tetrahedron consists of four oxygen
atoms packed closely around a single silicon
atom. Named for its shape (like a 3D pyramid).
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How do minerals form?

• 3 Ways
• Cooling of molten rock (lava or magma)
• Evaporation of liquid
• Saturated solutions

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Mineral Crystal Size

• Small Crystals indicates slow cooling of molten
  rock
• Large Crystals indicates fast cooling of molten
  rock

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Mineral Identification

• Color color is the first property you notice
  this is usually the 1st step in identification,
  but the least useful

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Quartz and Fluorite come in many different
colors



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Mineral Identification

• Hardness is a minerals resistance to being
  scratched

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Mohs Scale of Hardness

• Scale ranges from 1 to 10
• 1 is softest 10 is hardest

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Factoid

• What is the hardest substance on Earth??

• A diamond is the hardest substance
• (10 on Mohs scale)

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Mohs Hardness Scale
10 Diamond
9 Corundum
8 Topaz
7 Quartz
6 Feldspar
5 Apatite
4 Fluorite
3 Calcite
2 Gypsum
1 Talc
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Mineral Identification

• Streak the color of the powder left when a
  mineral is rubbed against a hard rough surface
  (usually unglazed porcelain)

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Testing Mineral Specimens
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Mineral Identification

• Luster the way light reflects from a minerals
  surface

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2 Types of Luster

• Metallic shiny
• Nonmetallic glassy, brilliant, greasy, oily,
  waxy, silky, or pearly

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Metallic Luster
Pearly Luster (Non-Metallic)
Vitreous Luster (Non-Metallic)
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Mineral Identification

• Cleavage mineral breaks along smooth surface
• Fracture mineral breaks unevenly (jagged)

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Mineral Identification

• Specific Gravity comparing density of a mineral
  to the density of water

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Mineral Identification

• Acid Test some minerals give off CO2 (carbon
  dioxide) when acid is added.

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If its a carbonate
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Mineral Usage

• Ore mineral resource mined for a profit
• Gem mineral that is beautiful, rare, and
  valuable

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Metals

• Metals are elements that have metallic luster,
  malleability, ductility, and conductivity

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Malleability

• the ability of a mineral to be hammered without
  breaking

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Ductility

• the ability to be pulled and stretched without
  breaking

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Conductivity

• the ability to conduct heat or electricity