Madocite

General Information:
 Chemical Formula:
Pb17(Sb,As)16S41
 Composition:
(Molecular Weight = 6,841.29 gm)
Antimony 24.91 % Sb
Arsenic 4.38 % As
Lead 51.49 % Pb
Sulfur 19.22 % S 
 Empirical Formula:
Pb17Sb14As4S41
 IMA Status:
Approved IMA 1967
 Locality:
Madoc, Ontario, Canada.
 Name Origin:
Named for the locality.
Physical Properties:
 Cleavage:
[010] Perfect
 Color:
grayish black.
 Density:
5.98
 Diaphaniety:
Opaque
 Habits:
Crystalline - Fine - Occurs as well-formed fine sized crystals., ,
 Hardness:
3 - Calcite
 Luster:
Metallic
 Streak:
grayish black
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