ENARGITE

    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 from Madielle quarries, Tuscany, Italy © Matteo Chinellato
Enargite and pyrite from Cerro de Pasco, Peru © Harald Biecker
Enargite from Butte, Montana, USA © Daniel Evanich
Twinned enargite from Carbonera Quarry, Tuscany, Italy © Italo Campostrini

Enargite in the World

The crystals exceptionally reach 15 cm in Quiruvilca (Peru). Centimeter-sized individuals are not rare in gold and silver deposits in Peru (Julcani, Pasto Bueno), Montana (superb group of 5 cm crystals at Leonard Mine, Butte), Taiwan or the Philippines (Lepanto, Luzon). At Tsumeb (Namibia), centimeter-sized crystals of enargite are tennantite pseudomorphs.

Enargite in France

In France, enargite is quite common in the sulfidic mass of Chizeuil near Chalmoux (Saône-et-Loire). It is also reported on numerous sites such as Chavaniac-Lafayette and Aurouze (Haute-Loire), Ris (Puy-de-Dôme), Poullaouen and Bolazec (Finistère), in Farges (Corrèze), in Villefranche-de-Rouergue (Aveyron). ), Cap Garonne (Var), etc...

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