Sylvanite or silver gold telluride, chemical formula (Ag,Au)Te2, is the most common telluride of gold.
Properties
The gold:silver ratio varies from 3:1 to 1:1. It is a metallicmineral with a color that ranges from a steely gray to almost white. It is closely related to calaverite, which is more purely gold telluride with 3% silver. Sylvanite crystallizes in the monoclinic 2/m system. Crystals are rare and it is usually bladed or granular. It is very soft with a hardness of 1.5–2. It has a high relative density of 8–8.2. Sylvanite is photosensitive and can accumulate a dark tarnish if it is exposed to bright light for too long.