manganotantalite

Manganotantalite is a manganese-rich oxide mineral of the tantalite group. It represents the Mn-dominant endmember of the columbite-tantalite series, with the generalized chemical composition (Mn,Fe)Ta2O6, in which manganese largely substitutes for iron. In natural occurrences it forms solid solutions with other tantalum-bearing oxides, including ferro-tantalite and manganocolumbite.

Geology and occurrence: Manganotantalite occurs in granitic pegmatites and other rare-metal-bearing veins, as well as in placer deposits derived from these rocks. It is commonly found together with other tantalum- and niobium-bearing minerals such as tantalite, columbite, and related oxides. Commercial deposits have been identified in several regions, including Africa, South America, and parts of Australia and North America.

Physical properties: The mineral typically appears as dark brown to black, with an opaque appearance and a resinous to vitreous luster. It is relatively hard for an oxide mineral, about 6 to 6.5 on the Mohs scale, and has a high specific gravity, generally in the range of 7.5 to 8.0 g/cm3. Crystals, when present, are usually tabular or prismatic and may display good cleavage in one direction.

Economic significance: Manganotantalite is an important source of tantalum, a metal used primarily in electronic capacitors and specialty alloys. Ore processing yields Ta2O5, which is refined into metallic tantalum. Due to market fluctuations and supply concentration in certain regions, the mineral is of particular interest to the mining and minerals-processing sectors dealing with tantalum production.

See also: tantalite, ferro-tantalite, manganocolumbite.