Lanthanite

minerals

allanite

cerite-(Ce)

actinolite

Formulae:
lanthanite-(Ce): Ce2(CO3)3.8H2O
lanthanite-(La): La2(CO3)3.8H2O
lanthanite-(Nd): Nd2(CO3)3.8H2O
Hydrated normal carbonates
Specific gravity: lanthanite-(Ce) 2.76 lanthanite-(La) 2.61 lanthanite-(Nd) 2.81
Hardness: lanthanite-(Ce) 2½ lanthanite-(La) and lanthanite-(Nd) 2½ to 3
Streak: White (all)
Colour: lanthanite-(Ce) Yellowish white, pink, colourless lanthanite-(La) White, yellowish, pinkish, transparent lanthanite-(Nd) Pale purple, light pink
Solubility: Lanthanite-(Nd) is decomposed with effervescence by dilute hydrochloric acid (AM 66.637-638)
Environments

Hydrothermal 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-(Ce) (HOM).

Localities

At its type locality, Curitiba, Paraná, Brazil, lanthanite-(Nd) occurs in recent carbonate-rich sediments (AM 66.637-638).

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. Sometimes crystals to 1 mm are found in allanite-bearing actinolite skarn (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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