SYLVANITE
sylvanite, graphic tellurium
(noun) a silver-white mineral consisting of silver gold telluride; a source of gold in Australia and America
Source: WordNet® 3.1
Etymology
Noun
sylvanite (plural sylvanites)
(mineral) Silver gold telluride, a soft metallic mineral ranging in colour from steely gray to almost white.
Source: Wiktionary
Syl"van*ite, n. Etym: [So called from Transylvania, where it was
first found.] (Min.)
Definition: A mineral, a telluride of gold and silver, of a steel-gray,
silver-white, or brass-yellow color. It often occurs in implanted
crystals resembling written characters, and hence is called graphic
tellurium. [Written also silvanite.]
Source: Webster’s Unabridged Dictionary 1913 Edition