DOMEYKITE

    Class : Sulfides and sulfosalts
    Subclass : Arsenides
    Crystal system : Cubic
    Chemistry : Cu3As
    Rarity : Rare

Domeykite is a rare mineral from copper and silver deposits. like algodonite, its most common companion, it concentrates arsenic from hydrothermal copper veins and "red-beds" type deposits, in which it rubs shoulders with cuprite, native copper, native silver and commonly cobalt minerals. It was named in honor of the Chilean mineralogist Ignacio Domeyko, founder of the Coquimbo School of Chemistry and Mineralogy. Domeykite is generally massive, can form masses of several kilos and sometimes acquires a botryoidal or kidney-shaped appearance ; it is extremely rare in crystals. It has a strong metallic luster and a silvery-white to steel-gray color that quickly tarnishes in air, evolving into iridescent black-brown masses that stain the fingers. It is a very accessory ore of copper and exceptionally a fine stone.

Main photo : Domeykite in 864g nodule from Mohawk Mine, Michigan, USA © Rob Lavinsky

Domeykite in the World

The deposits which have provided good samples of domeykite are rare, we can cite the Mohawk mine (Michigan, USA) with masses of several kilos, Copiapo and Chañarcillo (Chile) and Talmessi (Iran).

Domeykite in France

In France, domeykite is known in the Vosges mine of Wasserfall, in the Provençal mine of Daluis (Alpes-Maritimes), at the Clochettes mine (Hautes-Alpes), in Rabejac (Hérault) and in Lubilhac (Haute-Loire). 

Right photo : Domeykite and cuprite from Roua Mines, Daluis, Alpes-Maritimes, France © Pascal Chollet

Twinning

No twin known for this mineral species.

Fakes and treatments

No fake listed for this mineral species.


Hardness : 3 to 3.5
Density : 7.2 to 7.9
Fracture : Irregular
Streak : Black

TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None

Solubility : Nitric acid


Magnetism : None
Radioactivity : None