Minerals

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Minerals

• Formation, Characteristics and Identifying
  Properties

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Why study minerals?

• Minerals are important in our everyday lives...

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Some Uses (from USGS web site)

• Drywall is made from gypsum,
• Concrete in the foundation is made with limestone
  and aggregate reinforced with steel rebar,
• Bricks are made from clay,
• Titanium oxide is used to make paint,
• Silica is used to make windows,
• Electrical wiring is made from copper,
• Iron and copper are used to make pipes for
  plumbing, and
• Faucets contain various combinations of iron,
  chromium, nickel, and molybdenum combined to make
  stainless steel.

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So Now...What is a Mineral?

• A Naturally occurring
• Inorganic
• Homogenous
• Crystalline
• Single solid substance

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Asbestos

• All pictures are from

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Calcite

• note shape of crystal

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Garnet

• NY State Mineral

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Diamond

• The hardest mineral

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So...what is a crystal?

• A solid with a regular geometric shape resulting
  from the internal arrangement of atoms which make
  it up
• 6 basic shapes

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Crystal Shapes

• Cubic (halite)
• Hexagonal (quartz)
• Orthorhombic
• Monoclinic (calcite)
• Tetragonal
• Triclinic

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How Do Minerals Form?

• Cooling of magma (crystallization)
• Heat and pressure (recrystallization)
• Evaporates or precipitates from seawater

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What Determines the Size of the Crystal/Mineral?

• Cooling time
• coarse or large crystals have a long cooling time
• fine or small crystals have a short cooling time

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Identifying Minerals

• We use observable and testable characteristics to
  identify minerals

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Easily Observable Characteristics

• Color
• Luster(way the mineral reflects light)
• Crystal Shape

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Testable Characteristics

• Hardness (Mohs Scale)
• Streak (color of mineral in powdered form)
• Acid Test
• Cleavage vs. Fracture
• Specific Gravity
• Fluorescence

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Color

• This is the least reliable property to use to
  identify a mineral

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Luster

• Metallic or
• Non-metallic

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Streak

• Rub mineral along porcelain streak plate

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Hardness-Mohs Scale use tools to test each
mineral by scratching it against the tool. If
the mineral can scratch the tool then it is harder
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Cleavage vs. Fracture

• This is the way the mineral breaks -if it breaks
  along a plane then it cleaves, if it shatters
  then it fractures

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Cleavage-way mineral breaks
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Fracture
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acid test bubbles (releases carbon dioxide gas)
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Special Properties

• Fluoresence glows under blue light
• Double Refraction see words or images twice
  when looking through the mineral
• Magnetic will attract metals like a magnet

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Use these tests to help you identify minerals in
lab...