Cerianite-(Ce), Lanthanite-(Nd)

Specimen ID: CH5-0QE

Mineral(s)
Cerianite-(Ce) : (Ce4+,Th)O2
Lanthanite-(Nd) : (Nd,La)2(CO3)3·8H2O
Locality
Mindat locality:
Events

Photo added to mindat.org

Quite a unique example of a product of lateritic weathering of a REE-rich carbonatite: light brown tiny and rather ugly microcrystals of cerianite-(Ce) - one of three currently confirmed mineral species with tetravalent cerium (compare stetindite-(Ce) and dyrnaesite-(La)) - with white coatings of Nd-dominant member of the lanthanite group. Prior to the weathering Ce was associated with other REEs, but due to the weathering it was oxidized and as such separated from them. Cerium has the strongest affinity for the +4 oxidation state, but some other REEs may behave in a similar way at least in the lab (especially Tb, and to some extent also Pr and Nd).
Łukasz Kruszewski - 1st November 2018

Photo added to mindat.org

Quite a unique example of a product of lateritic weathering of a REE-rich carbonatite: light brown tiny and rather ugly microcrystals of cerianite-(Ce) - one of three currently confirmed mineral species with tetravalent cerium (compare stetindite-(Ce) and dyrnaesite-(La)) - with white coatings of Nd-dominant member of the lanthanite group. Prior to the weathering Ce was associated with other REEs, but due to the weathering it was oxidized and as such separated from them. Cerium has the strongest affinity for the +4 oxidation state, but some other REEs may behave in a similar way at least in the lab (especially Tb, and to some extent also Pr and Nd).
Łukasz Kruszewski - 1st November 2018

Photo added to mindat.org

Quite a unique example of a product of lateritic weathering of a REE-rich carbonatite: light brown tiny and rather ugly microcrystals of cerianite-(Ce) - one of three currently confirmed mineral species with tetravalent cerium (compare stetindite-(Ce) and dyrnaesite-(La)) - with white coatings of Nd-dominant member of the lanthanite group. Prior to the weathering Ce was associated with other REEs, but due to the weathering it was oxidized and as such separated from them. Cerium has the strongest affinity for the +4 oxidation state, but some other REEs may behave in a similar way at least in the lab (especially Tb, and to some extent also Pr and Nd). Not sure what the yellow stuff is.
Łukasz Kruszewski - 1st November 2018
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