Cobaltite - Encyclopedia

    Class : Sulfides and sulfosalts
    Subclass : Sulfides
    Crystal system : Orthorhombic
    Chemistry : CoAsS
    Rarity : Uncommon

Cobaltite is probably the most common of the cobalt minerals. It is found associated with other arsenides or sulfides of nickel and cobalt in high temperature hydrothermal mineralizations (veins, pyrometasomatic deposits, etc...). Appreciable quantities of nickel and especially iron can replace cobalt. Its name is linked to its chemical composition. The crystals are very common : usually isometric and with striated faces, they are often pseudocubic, pseudo-octahedral, pentagonal pseudododecahedral and of mixed shapes ; rarely exceeding one centimeter. Cobaltite can also be massive, grainy or compact. Its color ranges from silver white with pink highlights to metallic gray with a purplish tint. Cobaltite was once a major source of cobalt, less popular today.

Main photo : Cobaltite from Håkansboda, Bergslagen mining district, Sweden © Kristalle

Cobaltite from Tunaberg Cu-Co Ore Field, Tunaberg, Nyköping, Södermanland County, Sweden © Harold Moritz

Cobaltite in the World

Superb crystals come to us from Scandinavian deposits, notably Tunaberg (Sweden) and Skutterud, near Drammen (Norway) and measure up to 8 cm ; in this second deposit it crystallizes in metamorphic limestones. Schneeberg (Saxony, Germany) also delivered beautiful crystals. Cobaltite is present in numerous Australian and Canadian deposits, as well as in Bou Azzer (Morocco).

Cobaltite in France

In France, cobaltite is reported in many occurrences such as Marsanges (Haute-Loire), Chessy (Rhône), Poullaouen (Finistère), Lacaune (Tarn), Cap Garonne (Var), etc... however no major crystallization is to be noted.


Twins are known around [111] and with {011} and {111} as composition planes.

Fakes and treatments

No fake identified for this mineral species.

Hardness : 5.5
Density : 6.33
Fracture : Irregular
Streak : Gray-black

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

Solubility : Nitric acid

Magnetism : None
Radioactivity : None