| Enargite | |
|---|---|
 | |
| General | |
| Category | Sulfosalt mineral |
| Formula | Cu3AsS4 |
| IMA symbol | Eng[1] |
| Strunz classification | 2.KA.05 |
| Crystal system | Orthorhombic |
| Crystal class | Pyramidal (mm2) H-M symbol: (mm2) |
| Space group | Pmn21 |
| Unit cell | a = 7.407(1), b = 6.436(1) c = 6.154(1) [Å]; Z = 2 |
| Identification | |
| Color | Grayish black to iron black; gray to pale pink-brown, deep red internal reflections in polished section |
| Crystal habit | Tabular to prismatic crystals, striated parallel to {001}; massive |
| Twinning | Twin plane {320} common, rarely as interpenetrating pseudohexagonal trillings |
| Cleavage | Perfect on {110}, distinct {100} and {010} |
| Fracture | Uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 3 |
| Luster | Metallic to dull |
| Streak | Black |
| Diaphaneity | Opaque |
| Specific gravity | 4.4 to 4.5 |
| References | [2][3][4] |
Enargite is acopperarsenicsulfosalt mineral with formula Cu3AsS4. It takes its name from the Greek wordenarge 'distinct'. Enargite is a steel gray, blackish gray, to violet black mineral with metallic luster. It forms slenderorthorhombic prisms as well as massive aggregates. It has ahardness of 3 and aspecific gravity of 4.45.
Enargite isdimorph of the tetragonalluzonite.[2]
It is a medium to low temperaturehydrothermal mineral occurring withquartz,pyrite,sphalerite,galena,bornite,tetrahedrite–tennantite,chalcocite,covellite andbaryte.[4] It occurs in the mineral deposits atButte, Montana,San Juan Mountains,Colorado and at bothBingham Canyon andTintic, Utah. It is also found in the copper mines ofCanada,Mexico,Argentina,Chile,Peru, and thePhilippines.
Enargite was originally described as a new species from the copper mines of the San Francisco vein,Junin Department,Peru. The name is from Greekέναργής ("distinct"), in reference to its distinct cleavage.[2][4]
Enargite is related tolazarevicite (named after M. Lazarevic), which has the same chemical formula, but cubic crystalline structure.[5]
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