Loparite-(Ce)
General
CategoryOxide minerals
Formula
(repeating unit)		(Ce,Na,Ca)(Ti,Nb)O3
IMA symbolLop-Ce[1]
Strunz classification4.CC.35
Crystal systemLoparit-(Ce)-Q: tetragonal[2]
Loparit-(Ce)-O: orthorhombisch[2]
Loparit-(Ce)-C: cubic[3]
Identification
ColorBlack to grey-brown in thin section
Crystal habitCubic and octahedral crystals and massive
TwinningPenetration twins common on [111]
Cleavage[100] Imperfect
Fractureuneven
TenacityBrittle
Mohs scale hardness5.5 - 6.0
LusterMetallic to sub-metallic
Streakreddish brown
Diaphaneityopaque, transparent in thin fragments
Specific gravity4.60-4.89
Optical propertiesIsotropic, anomalously anisotropic
Refractive indexn = 2.26–2.38
References[4]

Loparite-(Ce) is a granular, brittle oxide mineral of the perovskite class. It is black to dark grey and may appear grey to white in reflected light on polished thin section with reddish brown internal reflections.[5] It has the chemical formula of (Ce,Na,Ca)(Ti,Nb)O3.[4] Nioboloparite is a variation of Loparite-(Ce) containing niobium.[6]

Loparite occurs as a primary phase in nepheline syenite intrusions and pegmatites. It is also found replacing perovskite in carbonatites.[4]

Loparite was first described for an occurrence in the Khibiny and Lovozero massifs, Kola peninsula in northern Russia.

Etymology

The term originates from the word Lopar, the (former) Russian name for the Sami indigenous inhabitants of the Kola peninsula, and the cerium content.[4][5][6]

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. 1 2 Mitchell R H, Burns P C, Chakhmouradian A R (2000) The crystal structures of loparite-(Ce), The Canadian Mineralogist 38, 145-152.
  3. ↑ Zubkova, N. V., Arakcheeva, A. V., Pushcharovskii, D. Y., Semenov, E. I., & Atencio, D. (2000). Crystal structure of loparite. Crystallography Reports, 45(2), 210-214.
  4. 1 2 3 4 "Loparite-(Ce)" (PDF). Mineral Handbook. Mineral Data Publishing. 2005. Retrieved 2008-07-19.
  5. 1 2 Loparite-(Ce) on Webmineral
  6. 1 2 Loparite-(Ce) on Mindat.org
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