Formula: CeO2
Simple oxide, uraninite group
Specific gravity: 7.216
Colour: Dark green-amber



At Morro do Ferro, Poços de Caldas, Poços de Caldas alkaline complex, Minas Gerais, Brazil, cerianite-(Ce) is a secondary mineral weathered from phonolite and nepheline syenite. Associated minerals include hydrobiotite, kaolinite and limonite (HOM).

At Gakara Project, Bujumbura Rural Province, Burundi, cerianite-(Ce) is associated with fluocerite and bastnäsite (HOM).

At the type locality, the Dominion Gulf Company claims, Lackner Township, Sudbury District, Ontario, Canada, cerianite-(Ce) occurs sparingly, in partially absorbed inclusions of wall-rock in a dikelike zone of carbonate rock cutting nepheline syenite. Associated minerals include nepheline, tremolite, feldspar, apatite, magnetite, ilmenite and calcite (HOM).

At Sushina Hill, Purulia District, West Bengal, India, cerianite-(Ce) occurs in nepheline syenite gneiss. Hydrothermal cerianite-(Ce), formed by the decomposition of eudialyte in the agpaitic rocks, occurs as small rounded crystals (MM 77.3137-3153).

At Kåbuland, Iveland, Agder, Norway, cerianite-(Ce) occurred in a pegmatite associated with fluocerite, bastnäsite and törnebohmite (HOM).

At the Kerimasi volcano, Monduli District, Arusha Region, Tanzania, cerianite-(Ce) occurs as rounded grains up to 5 μm across in a block of highly altered calcite carbonatite lava, and as euhedral crystals up to 200 μm across in carbonatite-derived eluvial deposits in the Kisete and Loluni explosion craters in the Gregory Rift. The cerianite-(Ce) is considered to be a late-stage secondary mineral in the carbonatitic rocks (MM 75.2813-2822).

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