What is "pyrochlore"

Pyrochlore \Pyr"o*chlore\, n. [Pyro- + Gr. ? pale green.] (Min.) A niobate of calcium, cerium, and other bases, occurring usually in octahedrons of a yellowish or brownish color and resinous luster; -- so called from its becoming grass-green on being subjected to heat under the blowpipe.

n. (context mineral English) A mineral whose composition is that of a mixed niobate mostly of sodium, calcium and cerium, (sodium,calcium)₂niobium₂oxygen₆(hydroxide,fluorine).

Pyrochlore ( Na, Ca) Nb O( OH, F) is a solid solution between the niobium end member (pyrochlore) and the tantalum end member ( microlite).