General Information:
Chemical Formula:
Pb2Bi2S5
Composition:
(Molecular Weight = 992.69 gm)
Bismuth 42.10 % Bi
Lead 41.75 % Pb
Sulfur 16.15 % S
Empirical Formula:
Pb2Bi2S5
Locality:
Silver Mine at Cosala, Sinaloa, Mexico.
Name Origin:
Named after its locality. Bjelkite is named after the Bjelke mine at Nordmark, Vermland, Sweden.
Physical Properties:
Cleavage:
[010] Good
Color:
gray, steel gray, or silver white.
Density:
6.4 - 6.8, Average = 6.6
Diaphaniety:
Opaque
Habits:
Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), Massive - Fibrous - Distinctly fibrous fine-grained forms.,
Hardness:
2.5-3 - Finger Nail-Calcite
Luminescence:
Non-fluorescent.
Luster:
Metallic
Streak:
black
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