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
Name Origin:
Named after the French mining engineer, C. L. Boulanger (1810-1849). Later name from an occurrence near Mullan, Idaho.
Physical Properties:
Cleavage:
[001] Indistinct, [010] Indistinct
Color:
lead gray, blue gray, or gray.
Density:
5.7 - 6.3, Average = 6
Diaphaniety:
Opaque
Habits:
Acicular - Occurs as needle-like crystals., Massive - Fibrous - Distinctly fibrous fine-grained forms., Plumose - "Mica-like" minerals forming aggregates of plume-like forms.
Hardness:
2.5 - Finger Nail
Luminescence:
None.
Luster:
Metallic
Streak:
reddish brown
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