Mineral Database

Mineral Database
Mineralogy of Wales

Lanthanite-(Ce)

Crystal System: Orthorhombic
Formula: (Ce,La,Nd)2(CO3)3.8H2O
Status of Occurrence: Confirmed Occurrence - Type Locality In Wales
Distribution: Rare
Chemical Composition: Cerium lanthanum neodymium carbonate hydrate
Method(s) of Verification: Britannia Mine - XRD & EMPA (University of Manchester).

SEM image of platy crystals of lanthanite-(Ce) coated by malachite from the type locality, Britannia Mine, Snowdonia, Gwynedd. Type specimen, National Museum of Wales Collection (NMW 84.6G.M.1). © National Museum of Wales.

Colourless platy lanthanite-(Ce) crystals coated with malachite. Field of view 7 mm wide. Type locality - Britannia Mine, Snowdon. National Museum of Wales Collection (NMW 84.6G.M.2). Photo D.I. Green, © National Museum of Wales.

Geological Context:
  • Supergene : post-mining oxidation & weathering deposits
Introduction: lanthanite-(Ce) is an extremely rare secondary mineral, named in 1985 as the cerium (Ce) end member of the lanthanite series. The type locality (first discovery) for lanthanite-(Ce) is Britannia Mine on Snowdon, where it was found in oxidized copper ore associated with weathered rare earth-bearing host rock. The type specimen is housed in the National Museum of Wales Mineral Collection (NMW 84.6G.M.1).
Occurrence in Wales: the extremely rare mineral lanthanite-(Ce) was first described by Bevins et al. (1985) from material collected from the walls of Sneyd's Level in Britannia Mine on Snowdon. The name lanthanite-(Ce) was chosen as this represents the cerium-predominant member of the lanthanite group. At Britannia Mine, lanthanite-(Ce) typically forms colourless, transparent plates with ragged terminations, associated with small malachite spheres. Exceptionally crystals reach 5 x 5 x 0.5 mm in dimension, but more typically are around 1 mm across. Lanthanite-(Ce) has since been recorded from a number of other localities worldwide, but remains exceptionally rare.
Key Localities:
  • Britannia Mine, Snowdonia, Gwynedd: colourless, transparent plates covered by radiating tufts of malachite, and associated with brochantite, posnjakite and chalcoalumite occur on the walls and the back of Sneyd's Level (Bevins et al., 1985).
References:
  • Bevins, R.E., 1994 A Mineralogy of Wales  National Museum of Wales, Geological Series No. 16, Cardiff, 146pp.
  • Bevins, R.E., Rowbotham, G., Stevens, F.S., Turgoose, S., & Williams, P.A., 1985 Lanthanite-(Ce), (Ce,La,Nd)2(CO3)3.8H2O, a new mineral from Wales, U.K.  American Mineralogist, 70, 411-413.