Crystal System: Monoclinic
Status of Occurrence: Confirmed Occurrence - 1st UK recording
Chemical Composition: Lead antimony sulphide
Chemical Formula: Pb5Sb8S17
Method(s) of Verification: Bwlch Mine - EMPA (Bevins et al., 1988).
- Hydrothermal: epithermal polymetallic veins & pipes
Introduction: plagionite is found with stibnite, galena and various lead-antimony (Pb-Sb) sulphosalts in complex hydrothermal vein and breccia assemblages typical of the epithermal Pb-Sb association. In common with many of the Pb-Sb sulphosalts, plagionite is usually almost impossible to identify in hand specimen and even in polished section these minerals can be remarkably difficult to distinguish. Consequently, verification requires detailed analytical techniques in the majority of occurrences.
Occurrence in Wales: the only record of plagionite from Wales to date resulted from detailed investigations of the antimony mineralization at Bwlch Mine near Deganwy on the North Wales coast (Bevins et al., 1988).
- Bwlch Mine, Deganwy, Gwynedd: intergrown with other Pb-Sb sulphosalts and stibnite in small (<2 cm) patches and stringers associated with quartz in a stockwork-like group of veins hosted by altered spherulitic acid ash-flow tuff (Bevins et al., 1988).
- Bevins, R.E., Alderton, D.H.M. & Horak, J.M., 1988. Lead-antimony mineralisation at Bwlch Mine, Deganwy, Wales. Mineralogical Magazine, 52, 391-394.