Properties of Minerals

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Properties of Minerals
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What is a Mineral?
Minerals are formed in nature.
Minerals are solids.
Minerals have a crystalline, geometric structure.
Minerals are inorganic not made from a living
thing.
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Major Properties

• Color come in many different colors
• Luster the way a surface reflects light
• Streak the color of a mineral in powder form
• Cleavage the tendency of a mineral to break
  along flat surfaces
• Fracture the tendency of a mineral to break
  unevenly along curved or irregular surfaces
• Hardness a minerals resistance to being
  scratched
• Density ratio of mass to volume

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Color

• Impurities and other factors can give minerals
  their color

These minerals are ALL forms of quartz! Color is
not a reliable way to describe minerals.
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Color

• Exposure to weather or chemicals may change the
  color of minerals.

Pyrite turns grey and black.
Oxidation turns iron from silver to black to red!
Copper turns green!
Color is not a reliable property to use in the
identification of minerals!
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Color
Amethyst 68.00
Tanzanite 720.00
Sapphire 500.00
Diamond 3,000.00
Moissanite 349.oo
REAL Gold
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Luster

• plastic, dull, metallic, waxy, pearly, glassy,
  silky

pearly
waxy
metallic
metallic
dull
glassy, vitreous
resinous, plastic
silky, fibrous
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Streak

• Powder made from rubbing a mineral across a
  streak plate

Galena
Pyrite
Hematite
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Cleavage

• Minerals that break along even lines have
  cleavage.

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Types of Cleavage
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Fracture

• break along curved or irregular surfaces

Conchoidal, shell-shaped
fibrous
irregular
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Hardness

• Hardness can be measured using a scratch test
• using Mohs Hardness Scale, which compares
  minerals to each other
• using common items such as a fingernail, copper
  penny, steel knife blade, glass

A fingernail can scratch talc.
Quartz can scratch glass, but fluorite cannot.
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Density

• How much matter there is in a given space
• Density Mass divided by Volume

volume
mass
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Special Properties
Radioactivity
Chemical Reaction
Magnetism
Salty Taste But NEVER taste things in the lab!
Double Image
Fluorescence