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Cymraeg

Lanarkite

Crystal System: Monoclinic
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Lead oxysulphate
Chemical Formula: Pb2(SO4)O
Method(s) of Verification: Dolyhir Quarry - XRD; Eaglebrook Mine - visual identification; Frongoch Mine - XRD (Oxford University Museum) & EMPA.

Geological Context:

Lanarkite (white) within oxidized tennantite-galena-bearing veinstone. Dolyhir Quarry, Old Radnor, Powys. Photo D.I. Green, © D.I. Green.
A divergent spray of bladed lanarkite crystals from Frongoch Mine. Individual crystals to 2.5 mm in length. Steve Rust specimen and photo. © Steve Rust.
Introduction: lanarkite is a rare secondary lead mineral formed through the alteration of primary lead minerals both within the oxidized upper levels of hydrothermal veins and within mine spoil.
Occurrence in Wales: lanarkite was first recorded in Wales by Mason (1994), as part of an extensive partly dump-formed supergene assemblage at Frongoch Mine in the Central Wales Orefield. Microcrystals have since been described from Eaglebrook Mine also within the Central Wales Orefield and a discovery of in-situ lanarkite has been made at Dolyhir Quarry in the Welsh borderland, but lanarkite remains an extremely rare Welsh species represented by only a handful of specimens.

Key Localities:

There are no key localities for this specimen.

References:

  1. Cotterell, T.F., Green, D.I., Hubbard, N., Mason, J.S., Starkey, R.E. and Tindle, A.G., 2011. The Mineralogy of Dolyhir Quarry, Old Radnor, Powys, Wales. UK Journal of Mines and Minerals, 32, 5-61.
  2. 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.
  3. Mason, J.S., 1994. A Regional Paragenesis for the Central Wales Orefield. Unpublished M.Phil thesis, University of Wales (Aberystwyth).
  4. Rust, S., Burchmore, S. & Foy, E., 1995. Some interesting new finds from the Nant-y-cagle mine. British Micromount Society Newsletter, 40, 8-10.

There are no references for this specimen.