CALAVERITE GOLD TELLURITE (thumbnail)

Calaverite, also known as gold telluride, is a rare metallic mineral characterized by the chemical formula AuTe2, with about 3% of its gold content substituted by silver. Discovered in 1861 in Calaveras County, California, it was named after the county in 1868. This mineral typically exhibits a metallic sheen and can appear in colors ranging from silvery white to brassy yellow. It is closely associated with sylvanite, another gold-silver telluride, which contains a higher silver content. Additionally, krennerite is another mineral with the same formula but differing crystal structure. While calaverite and sylvanite are the primary telluride ores of gold, they are relatively minor sources of gold overall. Notably, calaverite was significant during the gold rushes in Western Australia in the 1890s. 

In terms of physical and chemical properties, calaverite forms monoclinic crystals that lack cleavage planes, exhibiting a specific gravity of 9.35 and a hardness of 2.5. The mineral is soluble in concentrated sulfuric acid, and when treated with hot sulfuric acid, it dissolves to produce a spongy mass of gold suspended in a red tellurium solution.