pyrochlore
/ˈpʌɪrə(ʊ)klɔː/noun
A niobium-containing mineral found chiefly in nepheline-syenite and pegmatitic rocks, and occurring as brown or yellowish octahedral crystals which may turn green (or other colours) when strongly heated. Also: any of a group of oxide minerals sharing the cubic (isometric) crystal structure of this mineral and containing niobium, tantalum, or titanium. Frequently attributive, especially in pyrochlore group.
- The members of the pyrochlore group have the general formula A2B2O6 or A2B2O7, where A may be sodium, potassium, calcium, barium, uranium, or certain other elements, and B may be niobium, tantalum, titanium, or certain other elements. The mineral pyrochlore is a niobate, hydroxide, and fluoride of calcium and sodium, (Ca,Na)2Nb2O6(OH,F). Crystal structure: cubic..
Origin
Mid 19th century; earliest use found in American Journal of Science. From German Pyrochlor from pyro- + ancient Greek χλωρός greenish-yellow.