sylvanite

n. [ Fr. Transylvania, where first found. ] (Min.) A telluride of gold and silver, (Au, Ag)Te2, of a steel gray, silver white, or brass yellow. It often occurs in implanted crystals resembling written characters, and hence is called graphic tellurium. H., 1.5-2. Sp.gr., 7.9-8.3. [ Webster 1913 Suppl. ]