Germanite

Germanite
Germanite, probably from the Tsumeb Mine, Oshikoto Region, Namibia.
General
Category	Sulfide mineral
Formula	Cu26Ge4Fe4S321
IMA symbol	Ger2
Strunz classification	2.CB.30
Dana classification	2.9.4.2
Crystal system	Isometric
Crystal class	Hextetrahedral (43m) H-M symbol: (4 3m)
Space group	P43n
Identification
Color	Reddish grey tarnishing to dark brown
Crystal habit	Usually massive; rarely as minute cubic crystals
Cleavage	None
Tenacity	Brittle
Mohs scale hardness	4
Luster	Metallic
Streak	Dark grey to black
Diaphaneity	Opaque
Specific gravity	4.4 to 4.6
Other characteristics	Cell data: a = 10.585 Å Z = 13
References	45

Germanite is a rare copper iron germanium sulfide mineral, Cu₂₆Fe₄Ge₄S₃₂. It was first discovered in 1922, and named for its germanium content.³ It is only a minor source of this important semiconductor element, which is mainly derived from the processing of the zinc sulfide mineral sphalerite.⁶ Germanite contains gallium, zinc, molybdenum, arsenic, and vanadium as impurities.³

Its type locality is the Tsumeb Mine in Namibia where it occurs in a hydrothermal polymetallic ore deposit in dolomite in association with renierite, pyrite, tennantite, enargite, galena, sphalerite, digenite, bornite and chalcopyrite.⁵ It has also been reported from Argentina, Armenia, Bulgaria, Cuba, Democratic Republic of Congo (Zaire), Finland, France, Greece, Japan, Republic of Congo (Brazzaville), Russia and the United States.³