Mineral - Sphalerite
Sphalerite
Chemical Properties
Mineral Class
Sulfides and sulfosalts
Toxicity
none
Formula
ZnS
Unit Cell
a=5.41 Z=6
Physical Properties
Hardness
3.5 - 4
Streak
brown
Density
Heavy (3,5-6)
Cleavage
Perfect after {011}
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
blackbrownredorangeyellowgreen
Birefringence
Luster
Adamantine
Transparency
translucent,
transparent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
isometric
Point Group
hextetrahedral - 4 3m
Space Group
F 4 3m (216)
Habit
coarse, dodecahedron, massive, Octahedron, Tetrahedron, Cube
Formation
(1) Primarily magmatic as an accessory mineral in mafic rocks, as well as hydrothermal through precipitation from metal-bearing solutions over a wide temperature range.
(2) Epigenetic through the circulation of hydrothermal fluids in carbonate rocks (Mississippi Valley type).
(3) Metamorphic through recrystallization and remobilization of pre-existing sulfide accumulations under anoxic conditions.
Paragenesis
Twinning
Contact twins after {111} - Spinel law
Rarity
Common
Synonyms
Sphalerite
Composition
Elements
Mass
Zn
66.98
Fe
0.15
S
32.78
Mexico (Palache et al. 1952)
Groups and Members
Sphalerite-Group