Mineral - Boulangerite
Boulangerite
Chemical Properties
Mineral Class
Sulfides and sulfosalts
Toxicity
low
Formula
Pb₅Sb₄S₁₁
Unit Cell
a=21.61 b=23.54 c=8.08 β=101° Z=8
Physical Properties
Hardness
2.5 - 3
Streak
black
Density
Very Heavy (>6)
Cleavage
Distinct after {100}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
blackgray
Birefringence
Luster
Metallic,
Silky
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /m (11)
Habit
fibrous, acicular
Formation
In hydrothermal ore deposits
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Boulangerite
Composition
Elements
Mass
Pb
55.28
Fe
0.39
Sb
25.40
S
18.19
USA (Palache et al. 1952)