Download Color of a mineral in its powdered form

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How are minerals identified?
Physical properties
Crystal Form
• External expression of the crystal structure
• Crystal growth is often interrupted because of competition
for space and rapid loss of heat
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The mineral garnet often exhibits good crystal form
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Quartz in Granite
Luster
Galena is a lead sulfide that
Copper (Cu)
Quartz (SiO2)
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displays _________ luster
Color
Generally unreliable for mineral identification
Different minerals can have the same color
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Quartz (SiO2) exhibits a variety of colors
Streak
Color of a mineral in its powdered form
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¢ Helpful in distinguishing different forms of the same
mineral
Hematite
Hardness
• Resistance of a mineral to abrasion or scratching
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Hardness
• Resistance of a mineral to abrasion or scratching
• Depends on the bonds in the crystal structure
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Hardness
• Resistance of a mineral to abrasion or scratching
• Depends on the bonds in the crystal structure
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• All minerals are compared to a standard scale: the
Mohs scale of hardness
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Cleavage
Tendency to break along planes of weak bonding
Produces flat, shiny surfaces
Described by resulting geometric shapes
-Number of planes
-Angles between adjacent planes
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Three examples of perfect cleavage – fluorite, halite, and calcite
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Cleavage
Galena (PbS)
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Muscovite (mica) cleavage
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Fracture
Absence of cleavage when a mineral is broken- all bonds are equally
strong (weak)
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Fracture - Olivine
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Specific Gravity
Ratio of the weight of a mineral to the weight of an equal volume of
water
Average Earth crust value is approximately 2.7 g/cm3
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Other properties
Magnetism
Reaction to hydrochloric acid
Double refraction
Taste
Smell
Radioactivity
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USES OF MINERALS
“ If you can’t grow it, you have to mine it!”
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USES OF MINERALS
Jewelry
USDA daily food requirements
Graphite in pencils
Metals (all originate from mining minerals)
Clays
Cement
Energy, etc., etc., etc.
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USES OF MINERALS
Visit the NDGS Minerals web site at:
www.ndsu.edu/nd_geology
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