Mineral - Chalcocite
Chalcocite
Chemical Properties
Mineral Class
Sulfides and sulfosalts
Toxicity
none
Formula
Cu₂S
Unit Cell
a=15.25 b=11.88 c=13.49 β=116° Z=48
Physical Properties
Hardness
2.5 - 3
Streak
blackgraygray black
Density
Heavy (3,5-6)
Cleavage
Indistinct after {110}
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
blackgray
Birefringence
Luster
Metallic
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
massive, prismatic, tabular
Formation
In the cementation zone of supergene copper deposits, in hydrothermal veins
Paragenesis
Twinning
Pseudohexagonal rotational twins after {110}; Cross-shaped interpenetrational twins after {032}
Rarity
Common
Synonyms
Chalcocite
Composition
Elements
Mass
Cu
79.67
Fe
0.14
S
20.16
USA (Palache et al. 1952)
Groups and Members
Chalcocite-Digenite-Group