Tellurides are minerals formed with the telluride anion (Te^2-). Both gold and silver form tellurides, the most common being a mineral called sylvanite [(Au,Ag)Te₄]. Gold and silver were mined extensively around the town of Telluride in Colorado, but interestingly no gold telluride minerals have been found there! Seems like the Chamber of Commerce needs to get on that one. The local mines were rich in lead, zinc, and copper as well.

Tellurium (Te, #74) is a metalloid in Group 16 of the periodic table. Groups (or “families”) are the columns in the table—the rows are called periods. Tellurium is in the same family as oxygen, sulfur, and selenium. There are fungi that can substitute tellurium for either selenium or sulfur in metabolic processes but it otherwise has no biological function.

Tellurium is usually obtained as a by-product of copper refining. Its primary use is in solar cells. Cadmium telluride (CdTe) panels are more efficient than the more common crystalline silicon types so expect demand for this rare element to increase.