Chalcostibite - Encyclopedia
Class : Sulfides and sulfosalts
Subclass : Sulfosalts
Crystal system : Orthorhombic
Chemistry : CuSbS2
Rarity : Uncommon to rare
Chalcostibite is a fairly rare sulfosalt from copper and antimony veins, associated with many other copper or antimony minerals, including chalcopyrite and tetrahedrite. Its name is linked to its chemical composition and comes from the Greek khalcos (copper) and the Latin stibium (antimony). It occurs in prismatic crystals, often elongated and striated in parallel, sometimes lamellar flattened according to {010}, as well as in lamellar to grained masses. Its color is iron gray to lead gray but chalcostibite is frequently covered with an alteration film of azurite or malachite.
Main photo : Chalcostibite from St-Pons, Alpes-de-Haute-Provence, France © Pascal Chollet
Chalcostibite in the World
Twinning and special crystallizations
A twin is known on {104}.
The crystals can be partially to completely transformed into blue azurite or malachite (pseudomorph), notably on the Moroccan deposit of Rar-el-Anz.
Fakes and treatments
No fakes recorded for this mineral species.
Hardness : 3 to 4
Density : 4.9 to 5.0
Fracture : Sub-conchoidal
Streak : Black
TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None
Solubility : Nitric acid
Magnetism : None
Radioactivity : None