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
IMA symbolCei-Ce[1]
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[2][3][4]

Cerianite-(Ce) is a relatively rare oxide mineral, belonging to uraninite group with the formula (Ce,Th)O
2.[4][5] It is one of a few currently known minerals containing essential tetravalent cerium, the other examples being stetindite and dyrnaesite-(La).[6][7]

Occurrence and association

Cerianite-(Ce) is associated with alkaline rocks, mostly nepheline syenites.[3] It may be found in carbonatites.[4] Cerianite-(Ce) associates with minerals of the apatite group, bastnäsite-group minerals, calcite, feldspar, "fluocerite", "hydromica", ilmenite, nepheline, magnetite, "törnebohmite" and tremolite.[3] It is the most simple cerium mineral known.[4]

Notes on chemistry

Beside thorium cerianite-(Ce) may contain trace niobium, yttrium, lanthanum, ytterbium, zirconium and tantalum.[3]

Crystal structure

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

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ↑ Mineralienatlas
  3. 1 2 3 4 "Cerianite-(Ce) - Handbook of Mineralogy" (PDF). Handbookofmineralogy.org. Retrieved 2016-03-04.
  4. 1 2 3 4 "Cerianite-(Ce): Cerianite-(Ce) mineral information and data". Mindat.org. Retrieved 2016-03-04.
  5. ↑ Graham, A.R., 1955. Cerianite CeO2: a new rare-earth oxide mineral. American Mineralogist 40, 560-564
  6. ↑ "Stetindite: Stetindite mineral information and data". Mindat.org. Retrieved 2016-03-04.
  7. ↑ "Dyrnaesite-(La): Dyrnaesite-(La) mineral information and data". Mindat.org. Retrieved 2016-03-04.
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