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Formula: Ce2(CO3)3.8H2O
Hydrated carbonate
Specific gravity: 2.76
Hardness: 2½
Streak: White
Colour: Yellowish white, pink, colourless
Environments
The lanthanites are rare secondary carbonates
typically formed by alteration or weathering from earlier rare-earth-element-bearing
minerals (Webmin). Lanthanite-(Ce) is associated with allanite-(Ce)
and cerite-(CeCa)
(HOM).
Localities
The type Locality for lanthanite-(La) is the Bastnäs Mines, Riddarhyttan, Skinnskatteberg, Västmanland County,
Sweden. Here lanthanite-(Ce) is also found, as a late-stage, low temperature mineral, occurring as a
crystalline film coating cracks in the
cerium ore
(Minrec 35.3.196-197).
At its type locality, the Britannia Mine, Mount Snowdon, Gwynedd, Wales, UK, lanthanite-(Ce) occurs as an
extremely rare secondary mineral in oxidised copper ore,
coated by malachite. Associated minerals include
brochantite,
posnjakite and rarely chalcoalumite. In the
immediate mine area, high concentrations of rare earth elements are present in the rhyolitic
intrusions. These intrusions contain La in the range 60-100 ppm, Ce 140-200 ppm and Nd 70-120ppm. The average abundances, by weight, in
the Earth's crust are La 34 ppm, Ce 60 ppm and Nd 33 ppm
(AM 70.411-413, MW).
At Saucon Township, Pennsylvania, USA, lanthanite-(Ce) is associated with
allanite-(Ce)
(HOM).
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