Crystal System: Monoclinic
Status of Occurrence: Discredited Occurrence
Distribution: See individual species entries for details
Chemical Composition: Gold silver telluride
Chemical Formula: (Au,Ag)2Te4
Method(s) of Verification: none

Chemical Group:

  • Sulphides

Geological Context:

  • Hydrothermal: mesothermal polymetallic veins
Introduction: sylvanite occurs in gold deposits in which gold and silver tellurides are important economic minerals. These may be low-temperature (epithermal type) or medium-temperature (mesothermal type).
Occurrence in Wales: the only report of sylvanite from Wales is that by Pryor (1988). He describes sylvanite associated with gold, acanthite and other telluride minerals including hessite, from Gwynfynydd Mine in the Dolgellau Gold-belt. No details with regard to the identification method have been given and the rather unusual mineral association has not been observed before or since this study. The general consensus among specialists on the area is that this is a misidentification.

Key Localities:

There are no key localities for this specimen.


  1. Pryor, M.J., 1988. Geological and fluid inclusion studies at Ogofau and Gwynfynydd gold mines, Wales. South African Journal of Geology, 91, 450-464.