Otavite

Crystal System: Trigonal
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Cadmium carbonate
Chemical Formula: CdCO3
Method(s) of Verification: Dolyhir Quarry - EDS and wet chemical analyses by M. Rothwell and XRD at Manchester Museum (MANCH:XRD337).

Chemical Group:

  • Carbonates

Geological Context:

  • Supergene: in situ natural oxidation & weathering deposits
Introduction: otavite is an extremely rare secondary carbonate formed in the oxidation zone of cadmium-bearing orebodies in association with smithsonite, cerussite, pyromorphite, azurite and malachite.
Occurrence in Wales: otavite in Wales is restricted to a single discovery made in the mid 1990s at Dolyhir Quarry in the Welsh Borderlands. At Dolyhir, cadmium occurs in the primary sulphide assemblage as greenockite, alteration of which has resulted in the formation of minute quantities of otavite.

Key Localities:

  • Dolyhir Quarry, Old Radnor, Powys: minute buff coloured rhombohedral crystal masses, with individual crystals reaching ca. 0.05 mm on edge and chalky white coatings associated with brown smithsonite (Cotterell et al., 2011).

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.