COLOR

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COLOR

• Color is not usually a definitive property of a
  mineral. Color will only be definitive is it is
  a major constituent in the mineral.
• A good example of this is malachite which is
  green from the Cu.
• However most minerals have a variety of colors.

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Some Colors of Quartz
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STREAK

• For opaque minerals, if you rub the sample across
  a streak plate, it will leave a colored powder.
  This streak is distinctive for minerals and is
  used to identify minerals.

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Varieties of Hematite
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Play of Colors Iridescence

• For example, plagioclase, variety labradorite
• Interference of light either at the surface or in
  the interior of a mineral--series of color--much
  the same as oil on water. Opal is another
  example.

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Plagioclase-variety Labradorite
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LUSTER

• Metallic or non-metallic
• Non-metallic vitreous or glassy silky
  resinous pearly greasy waxy, dull earthy

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Examples of metallic luster
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Example of non-metallic luster

• Vitreous--quartz

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Example of non-metallic luster

• Silky--example satinspar

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Example of non-metallic luster

• Resinous--sphalerite

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Example of non-metallic luster

• Pearly--Talc

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Example of non-metallic luster

• Dull--Kaolinite

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Example of non-metallic luster

• Earthy--Goethite (limonite)

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Example of non-metallic luster

• Waxy--serpentine

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LUMINESCENCE

• The emission of light not due to incandescence.
  For example, fluorescent minerals colors under
  ultraviolet light. Minerals include varieties
  of calcite, fluorite and scheelite.

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The fluorite on your left is fluorescing The
fluorite on your right is the correct color