Cerianite-(Ce)

Cerianite-(Ce) is a relatively rare oxide mineral, belonging to uraninite group with the formula (Ce,Th)O
2.[3][4] It is one of a few currently known minerals containing essential tetravalent cerium, the other examples being stetindite and dyrnaesite-(La).[5][6]

Cerianite-(Ce)
Yellow powder of the very rare mineral cerianite-(Ce) from Morro do Ferro, Caldas, Minas Gerais, Brazil.
General
CategoryOxide
Formula
(repeating unit)		(Ce,Th)O
2
Crystal systemIsometric
Crystal classHexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space groupFm3m
Unit cella = 5.42 Å; Z = 4
Identification
ColorDark greenish amber-yellow, yellow, buff
Crystal habitoctahedra; earthy, massive
DiaphaneityTranslucent or transparent
Density7.20 (synth. material, calc.; approximated)
Other characteristics Radioactive
References[1][2][3]

Occurrence and association

Cerianite-(Ce) is associated with alkaline rocks, mostly nepheline syenites.[2] It may be found in carbonatites.[3] Cerianite-(Ce) associates with minerals of the apatite group, bastnäsite-group minerals, calcite, feldspar, "fluocerite", "hydromica", ilmenite, nepheline, magnetite, "törnebohmite" and tremolite.[2] It is the most simple cerium mineral known.[3]

Notes on chemistry

Beside thorium cerianite-(Ce) may contain trace niobium, yttrium, lanthanum, ytterbium, zirconium and tantalum.[2]

Crystal structure

For details on crystal structure see cerium(IV) oxide. Both ceria and thoria have a fluorite structure.

References
  1. Mineralienatlas
  2. "Cerianite-(Ce) - Handbook of Mineralogy" (PDF). Handbookofmineralogy.org. Retrieved 2016-03-04.
  3. "Cerianite-(Ce): Cerianite-(Ce) mineral information and data". Mindat.org. Retrieved 2016-03-04.
  4. Graham, A.R., 1955. Cerianite CeO2: a new rare-earth oxide mineral. American Mineralogist 40, 560-564
  5. "Stetindite: Stetindite mineral information and data". Mindat.org. Retrieved 2016-03-04.
  6. "Dyrnaesite-(La): Dyrnaesite-(La) mineral information and data". Mindat.org. Retrieved 2016-03-04.
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