Mineral Database (Saesneg yn unig)

Mineral Database (Saesneg yn unig)
Mineralogy of Wales

Litharge

Crystal System: Tetragonal
Formula: PbO
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Lead oxide
Method(s) of Verification: Frongoch Mine - XRD (Natural History Museum, London).
Chemical Group:
  • Oxides & Hydroxides
Geological Context:
  • Supergene : post-mining oxidation & weathering deposits
  • Supergene : minerals on an artificial substrate
Introduction: litharge, dimorphous with massicot, forms alteration crusts on other lead-bearing minerals, in particular galena which has been subjected to alkaline conditions.
Occurrence in Wales: restricted to a single discovery, made on the dumps of Frongoch Mine in the Central Wales Orefield, where lead-bearing mine spoil had been dumped in close proximity to masonry containing lime mortar. The mortar having reacted to produce unusual alkaline conditions particularly favourable for the development of mineral species such as litharge and elyite (Green et al., 1996).
Key Localities:
  • Frongoch Mine, Devil's Bridge, Ceredigion: extremely rare, forming reddish octahedral crystals to 0.5 mm and amorphous masses to 0.4 mm, associated with cerussite, in an area of dumps containing masonry cemented by lime-rich mortar (Bevins, 1994; Green et al., 1996).
References:
  • Bevins, R.E., 1994 A Mineralogy of Wales  National Museum of Wales, Geological Series No. 16, Cardiff, 146pp.
  • Green, D.I., Rust, S.A. & Mason, J.S., 1996 Classic British mineral localities: Frongoch Mine, Dyfed.  UK Journal of Mines & Minerals, 17, 29-38.