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Crystal System: Triclinic
Status of Occurrence: Unconfirmed Occurrence
Distribution: Rare
Chemical Composition: Antimony oxysulphide
Chemical Formula: Sb2S2O
Method(s) of Verification: visual only.

Chemical Group:

Geological Context:

Steel-grey stibnite, partially altered to cherry-red ?kermesite from Bwlch Mine. Specimen 11 cm x 6 cm. National Museum of Wales Collection (NMW 85.70G.M.34), ex R.W. Barstow Collection. © National Museum of Wales.
Introduction: kermesite is a cherry-red secondary mineral, typically found as surface alteration of stibnite.
Occurrence in Wales: kermesite has never been fully verified from Wales. Bevins et al. (1988) and Bevins (1994) described possible kermesite from Bwlch Mine, Deganwy, forming cherry-red coatings on stibnite, but failed to confirm this through X-ray diffraction. Similarly cherry-red secondary coatings on a specimen of stibnite reputedly from the north coast of Anglesey have been suggested to be kermesite, but never verified (Bevins, 1994).

Key Localities:


  1. Bevins, R.E., 1994. A Mineralogy of Wales National Museum of Wales, Geological Series No. 16, Cardiff, 146pp.
  2. Bevins, R.E., Alderton, D.H.M. & Horak, J.M., 1988. Lead-antimony mineralisation at Bwlch Mine, Deganwy, Wales. Mineralogical Magazine, 52, 391-394.