Variscite

Crystal System: Orthorhombic
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Aluminium phosphate hydrate
Chemical Formula: AlPO4.2H2O
Method(s) of Verification: Pwll-du Head - XRD (National Museum of Wales, NMW X-1156 and 1236)

Geological Context:

  • Supergene: in situ natural oxidation & weathering deposits
Variscite from Pwlldu beach, Gower, South Wales. Field of view 4.5 mm wide. National Museum of Wales Collection (NMW 2001.52G.M.1). Photo T.F. Cotterell, © National Museum of Wales.
Introduction: variscite is typically deposited under surface conditions in cavities and breccias as a result of phosphate-bearing meteoric waters reacting with aluminous rocks.
Occurrence in Wales: variscite is a rare mineral in Wales, recorded only recently at two adjoining localities on the Gower in south Wales. It was discovered by Plant & Jones (2001) in debris derived from a small limestone quarry at Pwll-du Head, previously recorded for its occurrence of wavellite. Variscite typically forms in association with wavellite and has subsequently been identified on the nearby storm beach at Pwll-du, always as minute spherical patches in wavellite-bearing chert.

Key Localities:

  • Pwll-du Head, Bishopston, Gower, South Wales: small (<1 mm), colourless to orange-yellow rosettes of variscite associated with sea-green wavellite found in quarry debris at the foot of the bank (Plant & Jones, 2001).
  • Pwll-du storm beach, Bishopston, Gower, South Wales: similar to the occurrence at Pwll-du Head. Tiny pearly white spherical patches occur embedded within broken wavellite sprays collected from pebbles and boulders on the storm beach (T.F. Cotterell, unpublished data).

There are no key localities for this specimen.

References:

  1. Plant, S.P., & Jones, I.E., 2001. Wavellite and variscite on Gower, Swansea, South Wales. Journal of the Russell Society, 7 (2), 79-81.

There are no references for this specimen.