Glaucodot - Encyclopedia

    Class : Sulfides and sulfosalts
    Subclass : Sulfides
    Crystal system : Orthorhombic
    Chemistry : (Co,Fe)AsS
    Rarity : Rare

Glaucodot is a rare mineral present in high temperature hydrothermal deposits containing iron and cobalt, sometimes copper. Its structure is close to that of arsenopyrite with which it does not, however, form a continuous series : the iron contents of glaucodot in fact peak at 22%. Its name comes from the Greek glaukos (green-blue) and doter (donor) because it was used as a blue pigment in the glass industry. Glaucodot forms elongated prismatic crystals along [001], more rarely along [010], usually not exceeding 2 cm ; more rarely it forms pseudo-orthorhombic octahedra or lamellar aggregates. Twins in cruciform buildings are quite common. With a metallic luster and a tin-white color with a pinkish tint, glaucodot accompanies pyrite, arsenopyrite and the classic procession of cobalt and nickel minerals (nickeline, alloclasite, safflorite). It is a very marginal arsenic ore.

Main photo : Glaucodot from Håkansboda, Bergslagen mining district, Sweden © Rob Lavinsky

Twins are common on {101} and {012} forming crosses.

No fakes recorded for this mineral species.