Crystal System: Cubic
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Silver gold telluride
Chemical Formula: Ag3AuTe2
Method(s) of Verification: Deepford Brook: electron-microprobe spot analyses on individual gold grains carried out by the British Geological Survey (BGS).

Chemical Group:

  • Sulphides

Geological Context:

  • Sedimentary: allogenic (detrital)
Introduction: a rare silver-gold telluride which occurs as minute inclusions within gold.
Occurrence in Wales: inclusions of coloradoite, petzite and a Cu telluride are reported by Norton et al. (2000) in gold grains from a sample taken from just above the confluence of the Deepford Brook with the Afon Syfni, near Clarbeston in Pembrokeshire. Prior to this, petzite was tentatively identified as an 8 ┬Ám diameter grain associated with possible calaverite included within alluvial gold from the Afon Wen, near Dolgellau, Gwynedd (Leake et al., 1993).

Key Localities:

  • Deepford Brook, Clarbeston, Pembrokeshire: a sample (PW114) taken from just above the confluence of the Deepford Brook with the Afon Syfni was found to contain a well-defined type of gold with telluride inclusions (Norton et al., 2000). The tellurides coloradoite, petzite and a Cu telluride were found to be present, together with pyrite and pyrrhotite.


  1. Leake, R.C., Bland, D.J. and Cooper, C., 1993.. Source characterization of alluvial gold from mineral inclusions and internal compositional variation. Transactions of the Institution of Mining and Metallurgy. B102, 65-82.
  2. Norton, G.E., Cooper, D.C., Davies, J.R. and Cornwell, J.D., 2000. Evidence for gold mineralisation in the Lower Palaeozoic and Precambrian rocks of south-west Wales. BGS Research Report RR/00/10. DTI Minerals Programme Publication No. 5.