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