General Information:
Chemical Formula:
Mn++Mn+++6SiO12
Composition:
(Molecular Weight = 604.64 gm)
Manganese 63.60 % Mn
Silicon 4.64 % Si
Oxygen 31.75 % O
Empirical Formula:
Mn2+Mn3+6SiO12
Environment:
Manganese oxide mineral deposits. Metamorphic and secondary weathering environments
Locality:
Metamorphic, hydrothermal, and sedimentary rocks.
Name Origin:
Named after K. Braun (1790-1872) from Gotha, Germany.
Physical Properties:
Cleavage:
[111] Perfect
Color:
grayish black, brownish gray, or dark brownish black.
Density:
4.72 - 4.82, Average = 4.76
Diaphaniety:
Opaque
Habits:
Massive - Uniformly indistinguishable crystals forming large masses., ,
Hardness:
6-6.5 - Orthoclase-Pyrite
Luminescence:
Non-fluorescent.
Luster:
Sub Metallic
Streak:
brownish gray black
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