Germanite

Germanite is a rare copper iron germanium sulfide mineral, Cu₂₆Fe₄Ge₄S₃₂. It was first discovered in 1922, and named for its germanium content.[2] It is only a minor source of this important semiconductor element, which is mainly derived from the processing of the zinc sulfide mineral sphalerite.[5] Germanite contains gallium, zinc, molybdenum, arsenic, and vanadium as impurities.[2]

Germanite
Germanite, probably from the Tsumeb Mine, Oshikoto Region, Namibia. Specimen size 5 cm
General
Category	Sulfide mineral
Formula (repeating unit)	Cu26Ge4Fe4S32[1]
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 = 1[2]
References	[3][4]

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.[4] 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.[2]