Enargite - Encyclopedia
Class : Sulfides and sulfosalts
Subclass : Sulfides
Crystal system : Orthorhombic
Chemistry : Cu3AsS4
Rarity : Quite common
Enargite is a primary sulphide of medium-temperature hydrothermal deposits ; it is especially common in acidic epithermal veins, the result of aerial rhyodacitic volcanism. It is mainly associated with pyrite, tennantite, bornite, chalcopyrite and covellite. Its name comes from the Greek enarges (distinct), revealing its excellent cleavage. Enargite is most often massive, grayish-black in color with purplish reflections. The crystals are usually small, tabular flattened according to {001}, strongly striated, reminiscent of manganite. It is an accessory ore of copper and arsenic.
Main photo : 5 cm enargite from Quiruvilca Mine, Santiago de Chuco, Peru © Terry Burtzlaff
Enargite in the World
Twinning
Twins are common on {230}, sometimes cyclical with the shape of a star.
Fakes and treatments
No fake listed for this mineral species.
Hardness : 3
Density : 4.4 to 4.5
Fracture : Irregular
Streak : Black
TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None
Solubility : Aqua regia
Magnetism : None
Radioactivity : None