Enargite

Sulfosalt mineral
(repeating unit)Cu3AsS4IMA symbolEng[1]Strunz classification2.KA.05Crystal systemOrthorhombicCrystal classPyramidal (mm2)
H-M symbol: (mm2)Space groupPmn21Unit cella = 7.407(1), b = 6.436(1)
c = 6.154(1) [Å]; Z = 2IdentificationColorGrayish black to iron black; gray to pale pink-brown, deep red internal reflections in polished sectionCrystal habitTabular to prismatic crystals, striated parallel to {001}; massiveTwinningTwin plane {320} common, rarely as interpenetrating pseudohexagonal trillingsCleavagePerfect on {110}, distinct {100} and {010}FractureUnevenTenacityBrittleMohs scale hardness3LusterMetallic to dullStreakBlackDiaphaneityOpaqueSpecific gravity4.4 to 4.5References[2][3][4]

Enargite is a copper arsenic sulfosalt mineral with formula Cu3AsS4. It takes its name from the Greek word enarge, "distinct". Enargite is a steel gray, blackish gray, to violet black mineral with metallic luster. It forms slender orthorhombic prisms as well as massive aggregates. It has a hardness of 3 and a specific gravity of 4.45.

Enargite is dimorph of the tetragonal luzonite.[2]

Occurrence

It is a medium to low temperature hydrothermal mineral occurring with quartz, pyrite, sphalerite, galena, bornite, tetrahedrite–tennantite, chalcocite, covellite and baryte.[4] It occurs in the mineral deposits at Butte, Montana, San Juan Mountains, Colorado and at both Bingham Canyon and Tintic, Utah. It is also found in the copper mines of Canada, Mexico, Argentina, Chile, Peru, and the Philippines.

Enargite was originally described as a new species from the copper mines of the San Francisco vein, Junin Department, Peru. The name is from Greek έναργής ("distinct"), in reference to its distinct cleavage.[2][4]

Enargite is related to lazarevicite (named after M. Lazarevic), which has the same chemical formula, but cubic crystalline structure.[5]

References

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c http://www.mindat.org/min-1380.html Mindat
  3. ^ http://webmineral.com/data/Enargite.shtml Webmineral
  4. ^ a b c Handbook of Mineralogy
  5. ^ "Lazarevicite on Mindat". Retrieved 2009-06-06.

External links

Media related to Enargite at Wikimedia Commons

  • Crystal structure of enargite