Loparite-(Ce)

Loparite-(Ce)
General
Category Oxide minerals
Formula
(repeating unit)		 (Ce,Na,Ca)(Ti,Nb)O3
Strunz classification 4.CC.35
Crystal system Loparit-(Ce)-Q: tetragonal[1]
Loparit-(Ce)-O: orthorhombisch[1]
Loparit-(Ce)-C: cubic[2]
Identification
Color Black to grey-brown in thin section
Crystal habit Cubic and octahedral crystals and massive
Twinning Penetration twins common on [111]
Cleavage [100] Imperfect
Fracture uneven
Tenacity Brittle
Mohs scale hardness 5.5 - 6.0
Luster Metallic to sub-metallic
Streak reddish brown
Diaphaneity opaque, transparent in thin fragments
Specific gravity 4.60-4.89
Optical properties Isotropic, anomalously anisotropic.
Refractive index n = 2.26–2.38
References [3]

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.[4] It has the chemical formula of (Ce,Na,Ca)(Ti,Nb)O3.[3] Nioboloparite is a variation of Loparite-(Ce) containing niobium.[5]

Loparite occurs as a primary phase in nepheline syenite intrusios and pegmatites. It is also found replacing perovskite in carbonatites.[3]

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

Etymology

The term originates from the word Lopar, the Russian name for the Sami indigenous inhabitants of the Kola peninsula, and the cerium content.[3][4][5]

Notes

  1. 1 2 Mitchell R H, Burns P C, Chakhmouradian A R (2000) The crystal structures of loparite-(Ce), The Canadian Mineralogist 38, 145-152.
  2. ↑ 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.
  3. 1 2 3 4 "Loparite-(Ce)" (PDF). Mineral Handbook. Mineral Data Publishing. 2005. Retrieved 2008-07-19.
  4. 1 2 Loparite-(Ce) on Webmineral
  5. 1 2 Loparite-(Ce) on Mindat.org


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