Cu12SbAs4S13

Cu12SbAs4S13 is a copper sulfosalt mineral belonging to the tetrahedrite group, representing a mixed arsenic–antimony composition. It is commonly written as Cu12(Sb,As)4S13 to reflect the solid solution between tetrahedrite (Cu12Sb4S13) and tennantite (Cu12As4S13). In this sense, Cu12SbAs4S13 describes a tetrahedrite-like phase in which the Sb and As occupy the same metalloid site within the structure.

The mineral forms a complex copper-sulfur framework in which copper is bonded to sulfur, while the Sb and As atoms reside in tetrahedral sites within the crystal structure. The result is a metallic mineral with a relatively high density and a distinct, dark appearance. Typical physical properties include a metallic luster, a gray to brownish-black color, a black streak, and a Mohs hardness of about 3.5 to 4. It is opaque and commonly occurs as irregular grains or small crystals.

Cu12SbAs4S13 occurs in hydrothermal vein deposits associated with other copper- and sulfosalt minerals, often alongside quartz, calcite, sphalerite, galena, enargite, and other members of the tetrahedrite-tennantite series. It has a wide geographic distribution and has been reported in many major ore districts worldwide, reflecting the extensive solid solution between the endmembers Cu12Sb4S13 and Cu12As4S13.

Economically, tetrahedrite-group minerals, including arsenic-rich variants, are of interest as copper ore minerals. The presence of arsenic and antimony can influence processing and environmental considerations, but the mineral itself primarily serves as a copper resource in many hydrothermal ore systems.