Crystal System: Orthorhombic
Status of Occurrence: Discredited Occurrence
Distribution: See individual species entries for details
Chemical Composition: Lead gold tellurium antimony sulphide
Chemical Formula: Pb5Au(Te,Sb)4S5-8
Method(s) of Verification:
- Hydrothermal: mesothermal polymetallic veins
- Hydrothermal: epithermal polymetallic veins & pipes
Introduction: nagyagite typically occurs in precious metal deposits, including both mesothermal and epithermal gold-lodes. It is typically accompanied by other gold and silver tellurides.
Occurrence in Wales: the presence of 'nagyagite' was noted by Gilbey (1968), who described it occurring as thin contact-rims between native gold and tellurides in a sample from Clogau Mine, Bontddu, Gwynedd. However, subsequent work with the electron microprobe on this sample, by D.H.M. Alderton, indicated that the rim-forming phase was in fact native bismuth, a re-identification published by Mason et al. (2002). Therefore, nagyagite is not a valid Welsh species.
There are no key localities for this specimen.
- Gilbey, J.W., 1968. The mineralogy, paragenesis and structure of the ores of the Dolgellau Gold Belt, Merionethshire, and associated wall rock alteration. Unpublished Ph.D thesis, University of London, UK.
- Mason, J.S., Bevins, R.E. & Alderton, D.H.M., 2002. Ore Mineralogy of the mesothermal gold lodes of the Dolgellau Gold Belt, North Wales. Transactions of the Institution of Mining and Metallurgy (Section B, Applied earth science), 111, B203-B214.