Falkmanite

General Information:
 Chemical Formula:
Pb5Sb4S11
 Composition:
(Molecular Weight = 1,875.73 gm)
Antimony 25.96 % Sb
Lead 55.23 % Pb
Sulfur 18.80 % S 
 Empirical Formula:
Pb5Sb4S11
 Environment:
Probably identical with boulangerite.
 IMA Status:
Not IMA Approved
Physical Properties:
 Cleavage:
[???] Good
 Color:
lead gray or pink brown.
 Density:
6.31
 Diaphaniety:
Opaque
 Hardness:
2-3 - Gypsum-Calcite
 Luster:
Metallic
 Streak:
brownish gray
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