Weibullite

General Information:
 Chemical Formula:
Pb6Bi8(S,Se)18
 Composition:
(Molecular Weight = 3,679.81 gm)
Bismuth 45.43 % Bi
Lead 33.78 % Pb
Selenium 8.58 % Se
Sulfur 12.20 % S 
 Empirical Formula:
Pb6Bi8S14Se4
 Locality:
Falun, Sweden.
 Name Origin:
Named for Mats Weibull (1856-1923), Swedish mineralogist.
Physical Properties:
 Cleavage:
[???] Good
 Color:
steel gray.
 Density:
6.97 - 7.145, Average = 7.05
 Diaphaniety:
Opaque
 Habits:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Massive - Fibrous - Distinctly fibrous fine-grained forms.,
 Hardness:
2-3 - Gypsum-Calcite
 Luster:
Metallic
 Streak:
dark gray
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