Microlite was once[when? known as a pale-yellow, reddish-brown, or black isometric mineral tantalum (Na,Ca)2Ta2O6(O,OH,F). Today[when? it is a name of a group of oxide minerals of a similar stoichiometry having tantalum prevailing over titanium and niobium. The microlite group belongs to a large pyrochlore and constitutes an ore of 5.5 and a variable specific gravity of 4.2 to 6.4. It occurs as disseminated microscopic subtranslucent to opaque octahedral crystals of 2.0 to 2.2. Microlite is also called djalmaite, but both names are now obsolete.
"Microlite" occurs as a primary mineral in lithium-bearing granite pegmatites, and in miarolitic cavities in granites. Association minerals include: albite , beryl , tantalite.
"Microlite" was first described in 1835 for an occurrence on the Island of Uto, State of Stockholm, Sweden. A type locality is the Clark Ledges pegmatite, Chesterfield, Hampshire County, Massachusetts. The name is from Greek mikros for "small" and lithos for "stone."