AuTe2

AuTe2 is a binary compound of gold and tellurium, best known in nature by the mineral form calaverite. Calaverite is the natural telluride mineral of gold and was named after Calaveras County, California, where it was first described in the late 19th century.

Occurrence and structure: Calaverite occurs in hydrothermal veins associated with quartz, barite, cinnabar, pyrite, and other tellurides. It forms metallic crystals that are typically short prismatic or tabular, with a brassy to pale bronze color. It crystallizes in the tetragonal system and tends to be brittle.

Physical and chemical properties: Calaverite is a dense, opaque mineral with a metallic luster. It has a relatively low hardness on the Mohs scale and a high specific gravity due to the presence of gold. The compound has the formula AuTe2 and consists of gold coordinated with tellurium in a layered telluride structure.

Significance and processing: Calaverite is an important gold ore mineral. In mining and processing, telluride ores can be refractory to standard cyanidation and may require roasting or oxidative treatment to release gold. Tellurium, recovered from such ores, has commercial value for alloys, electrical and semiconductor applications.

Distribution: Beyond the type locality in California, calaverite has been reported in other gold-bearing regions worldwide, including parts of Canada, Chile, Russia, and Australia.