Enargite


Composition: Cu3AsS4
Crystal System : Orthorhombic
Colours: Steel-grey, dark-grey, black
Lustre : Metallic
Hardness (H) : 3
Specific Gravity (S.G) : 4.4-4.5
References: Gebhard (1999)

Distribution

Abundant. A widespread ore mineral throughout the Tsumeb deposit.

Occurrence

  • Hypogene
  • 1st Oxidation Zone
  • 2nd Oxidation Zone
  • 3rd Oxidation Zone

Notable Finds

Steel-grey prismatic crystals to 80 mm were found in the upper portion of the first oxidation zone. Many fine pseudomorphs of tennantite after enargite were found on 16 Level (Gebhard, 1999).

Paragenetic and General Notes

Crystals were relatively common between surface and 6 Level but, with increasing depth, the degree of alteration to tennantite (as pseudomorphs after enargite) increased (Gebhard, 1999).

Keller (1977) notes that enargite was the most important hypogene copper mineral in the upper levels, but that its occurrence as millimetre-sized grains meant that it was easily overlooked.

Enargite is reported to form pseudomorphs after the following minerals: azurite (rare); tennantite (rare).

The following minerals are reported to form pseudomorphs after enargite:  chalcocite (rare); duftite (rare); malachite (rare); smithsonite (rare); tennantite (common).