Mineral Database (Saesneg yn unig)

Mineral Database (Saesneg yn unig)
Mineralogy of Wales

Matildite

Crystal System: Hexagonal
Formula: AgBiS2
Status of Occurrence: Confirmed Occurrence - 1st UK recording
Distribution: Rare
Chemical Composition: Silver bismuth sulphide
Method(s) of Verification: Clogau Mine - electron microprobe (Naden (1988).
Chemical Group:
  • Sulphosalts
Geological Context:
  • Hydrothermal : mesothermal polymetallic veins
Introduction: matildite is found, with other bismuth minerals, in medium-temperature ore deposits.
Occurrence in Wales: only one occurrence, limited to a single microscopic grain, of matildite has been noted in Wales.
Key Localities:
  • Clogau Mine, Bontddu, Gwynedd: Naden (1988) recorded a single microscopic (40 µm) grain of matildite occurring within a complex assemblage with tellurobismuthite, tetradymite, galena, chalcopyrite, pyrrhotite, hessite, altaite, gold, ''wehrlite', cobaltite and native bismuth. The sample was obtained from the No. 4 Level below the main Llechfraith Adit.
References:
  • Naden, J., 1988 Gold mineralisation in the Caledonides of the British Isles with reference to the Dolgellau Gold Belt and the Southern Uplands of Scotland.  Unpublished Ph.D thesis, University of Aston, UK.