MINERALOGY

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MINERALOGY

• CRYSTAL SYSTEMS

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Symmetry
Mirror Plane imaginary plane that divides a
crystal into halves, each of which is the mirror
image of the other
Axis of Rotation imaginary line through a
crystal about which the crystal may be rotated
and repeat itself in appearance (1,2,3,4 or 6
times during a complete rotation)
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Tips for creating models

• Write your name on each model BEFORE folding and
  taping!
• Cut into the pattern rather than around it.
• Fold along each face intersection BEFORE taping
  into place.
• Have fun learning something new!

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IsometricSystem
c a
?
90
90
90
?
?
Pyrite, Galena, Halite, Fluorite, Garnet, Diamond
ISOMETRIC ? ? ? 90 a b c
b a
a
Unique Symmetry Four 3-fold axes
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TetragonalSystem
Wulfenite, Zircon, Chalcopyrite, Rutile
?
90
90
90
?
?
TETRAGONAL ? ? ? 90 a b ? c
c ? a
b a
a
Unique Symmetry One 4-fold axis
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HexagonalSystem
Quartz, Beryl (Emerald), Apatite,
Graphite, Corumdum (Ruby, Sapphire)
c gt a
HEXAGONAL ? 120, ? ? 90 a b ? c
Unique Symmetry One 6-fold axis
?
?
90
90
120
?
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OrthorhombicSystem
Sulfur, Barite, Olivine, Topaz
?
90
90
90
?
?
ORTHORHOMBIC ? ? ? 90 a ? b ? c
c ? a
b ? a
a
Unique Symmetry Three 2-fold axes
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MonoclinicSystem
Orthoclase, Malachite, Azurite, Gypsum, Mica, Talc
?
?90
90
90
?
?
MONOCLINIC ? ? 90, ? ? 90 a ? b ? c
c ? a
b ? a
a
Unique Symmetry One 2-fold axis
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TriclinicSystem
Unique Symmetry None
c ? a
?
a
?
?90
?90
?90
?
b ? a
TRICLINIC ? ? ? ? ? ? 90 a ? b ? c
Turquoise, Plagioclase Kyanite, Albite
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Crystal Systems
System Axes Angles Unique Symmetry Diagram Example
s Isometric abc ???90 Four
3-fold Pyrite, Halite, Galena, Garnet, Diamond,
Fluorite Tetragonal ab?c ???90 One
4-fold Wulfenite, Rutile, Zircon,
Chalcopyrite Hexagonal ab?c ?120,
??90 One 6-fold Quartz, Beryl (Emerald),
Apatite, Corundum (Ruby, Sapphire) Orthorhombic
a?b?c ???90 Three 2-fold Sulfur, Barite,
Olivine, Topaz Monoclinic a?b?c ??90,
??90 One 2-fold Orthoclase, Malachite, Azurite,
Mica, Gypsum , Talc Triclinic a?b?c ??????90 No
ne Turquoise, Kyanite, Albite, Plagioclase
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Crystal Systems
System Axes Angles Unique Symmetry Diagram Example
s Isometric Tetragonal Hexagonal Ort
horhombic Monoclinic Triclinic