Sphalerite

Physical Properties
Chemical formula ZnS
Class Sulfide
Crystal system Cubic
Habit Combinations of tetrahedra,
dodecahedra, and cubes
Commonly forms cleavable masses
Color Brown-orange-red
Colorless when pure
Brown
Black
Yellow
Hardness 3.5 to 4
Specific gravity 4.0
Cleavage Perfect dodecahedral {110}
Fracture Conchoidal
Luster Adamantine
Resinous
Transparency Transparent to opaque
Streak White to brown
or yellow
Optical Properties
PPL Colorless to pale brown
or yellow
Extremely high relief
Good cleavage
XPL Isotropic
δ None
Twinning Polysnthetic twins
are common
Special properties
May have faint garlic or sulfur
smell, especially if powdered
after Perkins, 355-356

Sphalerite in Hand Sample

Two small hand samples

Sphalerite on fossiliferous chert

Sphalerite in Thin Section

Thin Section GigaPans

Sphalerite in plane polars

Sphalerite in crossed polars

Sphalerite, PPL
Sphalerite, XPL

Further Reading

Sphalerite at webmineral.com

Sphalerite at mindat.org