Crystal System: Hexagonal
Status of Occurrence: Confirmed Occurrence - 1st UK recording
Distribution: Rare
Chemical Composition: Silver bismuth sulphide
Chemical Formula: AgBiS2
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 ┬Ám) 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.


  1. 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 Unpublished Ph.D thesis, University of Aston, UK.