Minerals

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Minerals
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Identifying Minerals

• Color
• Luster
• Streak
• Hardness

• Crystal Shape
• Acid Test
• Density
• Cleavage or Fracture

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Luster

• The way an mineral reflects light
• Metallic
• Non-metallic
• Pearly
• Waxy
• Glassy

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Streak

• This is the color of a mineral when crushed or
  streaked against a streak plate
• Sometimes the color of a mineral is very
  different in its streak form than in its whole
  form.
• i.e. pyrite is brassy yellow but leaves a
  green black streak

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Hardness What can I scratch?
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Cleavage or Fracture? (notes)

• If a mineral breaks into smooth shapes it is said
  to have cleavage.
• If a mineral breaks into uneven fragments it is
  said to fracture.

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Types of Cleavage

• The amount of smooth surfaces a broken mineral
  posses is the number of planes or directions of
  cleavage.

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Types of Cleavage

• One plane -a flat sheet i.e mica
• Two planes prismatic
• Three planes cubic i.e. halite

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Fracture

• Minerals which do not cleave, can fracture in two
  ways
• They can be irregular ( no pattern at all)
• OR
• They can have conchoidal fracture

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Crystal Shape

• When a mineral forms crystals, it can be helpful
  to examine their shape
• Quartz crystals have six sides
• Calcite crystal are rhombohedral

QUARTZ
CALCITE
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Mineral Groups

• Depending on the groups of elements in a mineral
  they can be placed into specific groups.

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Silicates (notes)

• Silicon and Oxygen minerals
• Atoms
• form a tetrahedron

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REMEMBER!!

• The properties of a mineral are determined by the
  internal arrangement of its atoms.