Pyrochlore Group - (Ca, Na)₂Nb₂O₆(O, OH, F)

Habit: Usually octahedral crystals, sometimes modified by cube faces; Brown, yellow-brown, reddish brown, orange, black Vitreous, resinous Luster, transparent.

Environment: Pegmatites in nepheline syenites, granitic Pegmatites and greisens, carbonatites.

Etymology: Named from the Greek for "fire"and "green", because some specimens of the mineral turned green when ignited.

Was recently changed from a mineral name to a group of minerals