Germanite

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]

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]

Its type locality is the Tsumeb Mine in Namibia where it occurs in a hydrothermal polymetallic ore deposit in dolostone 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]

X-Ray Powder Diffraction[6]
d spacing 3.05 2.65 1.87 1.60 1.32 1.21 1.08 1.02
relative intensity 10 1 7 4 1 2 2 1

References

  1. ↑ American Mineralogist (1984) 69:943-947
  2. 1 2 3 4 http://www.mindat.org/min-1681.html Mindat.org
  3. ↑ http://webmineral.com/data/Germanite.shtml Webmineral
  4. 1 2 http://rruff.geo.arizona.edu/doclib/hom/germanite.pdf Handbook of Mineralogy
  5. ↑ U.S. Geological Survey (2008), "Germanium—Statistics and Information", U.S. Geological Survey, Mineral Commodity Summaries http://minerals.usgs.gov/minerals/pubs/commodity/germanium/
  6. ↑ Dana's New Mineralogy, 8th edition, Gaines et al., Wiley
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