Kentrolite

General Information:
 Chemical Formula:
Pb2Mn+++2Si2O9
 Composition:
(Molecular Weight = 724.44 gm)
Manganese 15.17 % Mn
Silicon 7.75 % Si
Lead 57.20 % Pb
Oxygen 19.88 % O 
 Empirical Formula:
Pb2Mn3+2Si2O9
 Locality:
Vermland, Sweden.
Physical Properties:
 Cleavage:
[110] Distinct
 Color:
dark reddish brown or reddish black.
 Density:
6.19
 Diaphaniety:
Translucent to subtranslucent
 Habits:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Crystalline - Fine - Occurs as well-formed fine sized crystals., Wheat Sheaf - Bundle shaped aggregates resembling wheat sheafs after hand reaping wheat.
 Hardness:
5 - Apatite
 Luster:
Sub Metallic
 Streak:
dark brown
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