Pyrochlore is an end member of a solid-solution series between itself and the mineral microlite . The two minerals have similar structures and properties, but microlite is the tantalum rich end member and pyrochlore is the niobium rich end member. The overall more common mineral microlite is found mostly in granitic pegmatite dikes and more rarely in the carbonatites. Pyrochlore is the more impure mineral of the two because it is more often accepting of the inclusion of elements such as tantalum, titanium, iron and uranium as well as the previously mentioned rare earth metals into its structure. Some variety names of pyrochlore are known.
Color is yellow, reddish-brown, red or black.
Luster can vary from vitreous, adamantine, greasy to resinous. Crystals are translucent with darker specimens being opaque. Fracture is conchoidal to uneven. Variation caused by extent of inclusion of trace metals into the structure. Streak is pale yellow to brown.