Sylvanite
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Sylvanite or Silver gold telluride, (Ag,Au)Te2, is the most common telluride of gold. The gold:silver ratio varies fromm 3:1 to 1:1. It is a metallic mineral with a color that ranges from a steely gray to almost white. It is closely related to calaverite. 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. If it is exposed to bright light for too long, it can accumulate a dark tarnish.
Sylvanite is found in Transylvania from which its name is derived. It is also found and mined in Australia in the East Kalgoorlie district. In Canada it is found in the Kirkland lake Gold District, Ontario and the Rouyn District, Quebec. In the U. S. it occurs in California and in Colorado where it was mined as part of the Cripple Creek ore deposit. Sylvanite is associated with native gold, quartz, fluorite, rhodochrosite, pyrite, acanthite, nagyagite, calaverite, krennerite, and other rare telluride minerals. It is found most commonly in low temperature hydrothermal vein deposits.
References and external links
- *Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0471805807
- Mineral Galleries - Sylvanite (http://mineral.galleries.com/minerals/sulfides/sylvanit/sylvanit.htm)
- Webmineral - Sylvanite (http://webmineral.com/data/Sylvanite.shtml)