Lengenbachite

General Information:
 Chemical Formula:
Pb6(Ag,Cu)2As4S13
 Composition:
(Molecular Weight = 2,153.32 gm)
Copper 1.48 % Cu
Silver 7.51 % Ag
Arsenic 13.92 % As
Lead 57.73 % Pb
Sulfur 19.36 % S 
 Empirical Formula:
Pb6Ag1.5Cu0.5As4S13
 Locality:
Lengenbach quarry, Binnental, Valais, Switzerland.
 Name Origin:
Named after its locality.
Physical Properties:
 Cleavage:
[???] Perfect
 Color:
gray blue or steel gray.
 Density:
5.8 - 5.85, Average = 5.82
 Diaphaniety:
Opaque
 Habits:
Tabular - Form dimensions are thin in one direction., ,
 Hardness:
1-2 - Between Talc and Gypsum
 Luster:
Metallic
 Streak:
black
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