Microlite is found mostly in granitic pegmatite dikes and more rarely in calcite rich rocks called carbonatites. The rarer pyrochlore on the other hand is more common to the carbonatites and alkalic pegmatites called nepheline syenites. The mineral gahnite also forms octahedrons but is neither a rare earth mineral nor apart of the pyrochlore Group of minerals. Gahnite is a member of the Spinel Group of oxide minerals. Its green color makes it easy to confuse with the green varieties of microlite, but microlite is generally denser and much softer.
Color is pale yellow, reddish-brown, red, olive or even emerald green.
Luster is vitreous to resinous. Crystals are generally translucent with darker specimens being opaque. Although the name microlite was applied to the mineral for the tiny crystals that were first found, larger crystals up to 2 cm have been found. Fracture is subconchoidal to uneven. Variation caused by extent of inclusion of trace metals into the structure.