Crystal System: Trigonal
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Lead iron phosphate sulphate hydroxide
Chemical Formula: PbFe3+3(PO)4(SO)4(OH)6
Method(s) of Verification: Frongoch Mine - XRD & semi-quantitative EDS (National Museum of Wales, X-ray number NMW X-1401).

Chemical Group:

  • Phosphates
  • Sulphates

Geological Context:

  • Supergene: post-mining oxidation & weathering deposits
  • Supergene: in situ natural oxidation & weathering deposits
Scanning electron micrograph of rhombic corkite crystals on goethite from Frongoch Mine. National Museum of Wales Collection (NMW 2005.10G.M.1). © National Museum of Wales.
Introduction: corkite is a rare secondary species typically found within phosphate-dominated secondary mineral assemblages, particularly associated with lead-rich orebodies.
Occurrence in Wales: corkite has only recently been discovered in Wales (Cotterell and Todhunter, 2007) forming, minute euhedral crystals in iron stained quartz veinstone from Frongoch mine, in the Central Wales Orefield. Only a very small number of specimens are known, but this reflects the inconspicuous nature of this species.

Key Localities:

  • Frongoch Mine, Devil's Bridge, Ceredigion: identified on specimens collected from the extensive dumps as minute (<0.3 mm) yellowish-green to olive-green rhombic crystals on goethite-coated quartz (Cotterell and Todhunter, 2007).

There are no key localities for this specimen.


  1. Cotterell, T.F. and Todhunter, P.K., 2007. Corkite and hinsdalite from Frongoch mine, Devil's Bridge, Ceredigion, Wales, including evidence to suggest that orpheite is a variety of hinsdalite. Journal of the Russell Society, 10, 57-64.

There are no references for this specimen.