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MINERALOGY
Some Common Minerals
Illustrated
by Charina Cameron
Mineral Groups
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Nearly 4000 minerals
Only a few dozen are abundant in Earth’s crust
These are the rock-forming minerals
8 elements comprise the bulk of these minerals
They also represent 98% of the continental crust:
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O
Si
Al
Fe
Ca
Na
K
Mg
47%
28%
8%
5%
4%
3%
3%
2%
Silicate minerals
Major Properties of Minerals
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Crystal form
Luster (metallic, non-metallic, etc.)
Colour (often due to impurities)
Streak (colour of powder)
Hardness (Moh’s scale: 1 to 10)
Cleavage
– none or up to 6 surfaces
– planes of weakness in crystal structure
• Fracture (conchoidal, etc.)
• Specific gravity
– density compared to water
– galena is much greater than quartz (2.65)
Special Mineral Properties
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Magnetic
Elastic
malleable
taste
smell
feel
– Soapy
– Greasy
• Double refraction
• Reaction to HCl
Moh’s HARDNESS SCALE
1
7
4
Quartz
Fluorite
Talc
8
Topaz
2
5
Gypsum
9
Apatite
6
3
Corundum
10
Orthoclase
Calcite
Diamond
Common Mineral Groups
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Sulfides
Oxides
Carbonates
Sulphates
Phosphates
Halides
Native elements
Silicates
S2O2(CO3)2(SO4)2(PO4)3F,Cl, etc.
Au, Cu, C, etc.
(SiO4)4-
SULFIDES
• Pyrite
• FeS2
• Sphalerite
• (Zn,Fe)S
Chalcopyrite
(Cu,Fe)S2
Galena
PbS
OXIDES
• Hematite
– Fe2O3
• Corundum
– Al2O3
Limonite
Magnetite
Fe2O3 nH2O
Fe3O4
CARBONATES
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Double refraction in Calcite
CaCO3
• Dolomite crystals
(Ca,Mg)CO3
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Siderite
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FeCO3
CARBONATES
• Calcite crystals from a vein in Wolfville Formation,
showing 3 perfect cleavages not at right angles
CARBONATES
• Hexagonal Calcite crystals from Scots Bay Fm
SULPHATES
• Gypsum
CaSO4nH2O
• Anhydrite CaSO4
PHOSPHATES
• Apatite
Ca3(PO4)2
HALIDES
• Fluorite
CaF2
4 cleavages
• Halite
NaCl
3 cleavages
at right angles
NATIVE ELEMENTS
• Sulphur
S8
• Gold
Au
tiny nuggets panned at
Ovens, Nova Scotia
• Graphite
C
• Diamond
C