Barysilite

General Information:
 Chemical Formula:
Pb8Mn(Si2O7)3
 Composition:
(Molecular Weight = 2,217.04 gm)
Manganese 2.48 % Mn
Silicon 7.60 % Si
Lead 74.77 % Pb
Oxygen 15.15 % O 
 Empirical Formula:
Pb8Mn2+3(Si2O7)
 Locality:
Franklin, Sussex Co., New Jersey, USA.
Physical Properties:
 Cleavage:
[???] Perfect
 Color:
white or gray.
 Density:
6.11 - 6.72, Average = 6.41
 Diaphaniety:
Transparent to translucent
 Habits:
Massive - Lamellar - Distinctly foliated fine-grained forms., ,
 Hardness:
3 - Calcite
 Luminescence:
Non-fluorescent.
 Luster:
Adamantine
 Streak:
white
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