Loparite

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loparite

[′lō·pə‚rīt]
(mineralogy)
(Ce,Na,Ca)2(Ti,Nb)2O6 A brown to black mineral; a variety of perovskite containing alkalies and cerium.

Loparite

 

a mineral of chemical composition (Na, Ce, Ca)2-(Ti, Nb)2O6. The principal admixtures are Sr, Y, and Th. Loparite crystallizes in the isometric system, forming primarily small (up to 2-3 mm) crystals, which generally occur as penetration twins. Loparite is structurally similar to perovskite and exhibits no cleavage. It is black, opaque, and has a semimetallic luster. Its hardness is 5.5-6, and its density 4,750-4,890 kg/m3. Loparite occurs in nepheline syenites (sometimes as one of the rock-forming magmatic minerals) and, more rarely, in pegmatites genetically related to nepheline syenites.