What is "graphic tellurium"

Sylvanite \Syl"van*ite\, 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.

n. a silver-white mineral consisting of silver gold telluride; a source of gold in Australia and America [syn: sylvanite]