Cerianite-(Ce)
Oxide mineral
From Wikipedia, the free encyclopedia
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]
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| Cerianite-(Ce) | |
|---|---|
Yellow powder of the very rare mineral cerianite-(Ce) from Morro do Ferro, Caldas, Minas Gerais, Brazil. | |
| General | |
| Category | Oxide |
| Formula | (Ce,Th)O 2 |
| IMA symbol | Cei-Ce[1] |
| Crystal system | Isometric |
| Crystal class | Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m) |
| Space group | Fm3m |
| Unit cell | a = 5.42 Å; Z = 4 |
| Identification | |
| Color | Dark greenish amber-yellow, yellow, buff |
| Crystal habit | octahedra; earthy, massive |
| Diaphaneity | Translucent or transparent |
| Density | 7.20 (synth. material, calc.; approximated) |
| Other characteristics |  Radioactive |
| References | [2][3][4] |
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
Crystal structure
For details on crystal structure see cerium(IV) oxide. Both ceria and thoria have a fluorite structure.