Acicular:
Long needle like crystals:
eg Gypsum CaSO4.2H2O
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Columnar:
Long but thick:
eg Quartz SiO2
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Equant:
Roughy equal in all dimensions
eg Olivine (Mg, Fe)2SiO4
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Bladed:
Long, flat byt narrow
eg Kyanite Al2SiO5
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Tabular:
Thin and flat
eg Muscovite KAl2(OH)2AlSi3O10
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Concretionary:
Roughly spherical concentric layers
eg Pyrite FeS2
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Botryoidal:
Rouded aggregates like a bunch of grapes
eg Pyrolusite MnO2
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Mammilary:
Breast like rounded surfaces
eg Haematite Fe2O3
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Pisolitic:
Pea-sized spherical concretions
eg Bauxite
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Oolitic:
Smaller concretions like fish eggs
eg Haematite Fe2O3
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Foliated:
Separable leaves or sheets
Molybdenite MoS2
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Radiating:
Needle-like crystals pointing outwards from a common
centre like a star burts.
eg Inesite H2(Mn,Ca)6Si6O19.3H2O
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Stalactitic:
Thin tapering columns
eg Apatite Ca5(F,Cl,OH)(PO4)3
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Dendritic:
Fern-like branching shapes
eg Pyrolusite MnO2
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Massive:
Compact with no particular shape
eg Rhodonite MnSiO3
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Fibrous:
Clusters of thin threads
eg Crysotile asbestos H4Mg3Si2O9
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