tetrahedrite

Tetrahedrite
A sample of grey tetrahedrite, with white quartz
General
Category	Mineral: sulfosalt
Chemical formula	(Cu,Fe)12Sb4S13
Identification
Molar mass	1,643.31 gm
Color	Steel gray to iron-gray
Crystal habit	massive to well formed crystals
Crystal system	Cubic
Cleavage	None
Fracture	Uneven
Mohs scale hardness	3½ - 4
Luster	Metallic
Streak	Black
Diaphaneity	Opaque

Tetrahedrite is a copper antimony sulfosalt mineral with formula: (Cu,Fe)₁₂Sb₄S₁₃. It is the antimony endmember of the continuous solid solution series with arsenic bearing tennantite. Pure endmembers of the series are seldom if ever seen in nature. Of the two, the antimony rich phase is more common. Other elements also substitute in the structure, most notably iron and zinc along with less common silver, mercury and lead. Bismuth also substitutes for the antimony site and bismuthian tetrahedrite or annivite is a recognized variety. The related, silver dominant, mineral species freibergite, although rare, is notable in that it can contain up to 18% silver.

Tetrahedrite gets its name from the distinctive tetrahedron shaped cubic crystals. The mineral usually occurs in massive form, it is a steel grey to black metallic mineral with Mohs hardness of 3.5 to 4 and specific gravity of 4.6 to 5.2.

It occurs in low to moderate temperature hydrothermal veins and in some contact metamorphic deposits. It is a minor ore of copper and associated metals. It was first described in 1845 for occurrences in Freiberg, Saxony, Germany.

See also

• Bornite
• Cuprite
• Tennantite

References

• Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., Wiley, ISBN 0-471-80580-7
• Mindat
• Mineral galleries
• Webmineral data