21 Photos
Ferrocolumbite
Chemical Formula	Fe2+Nb2O6
Species	Oxides & Hydroxides
Crystal System	Orthorhombic
Mohs Scale	6
Specific Gravity	5.3-7.3
Color	Black, brownish black.
Streak	blackish brown
Luster	sub-metallic
Cleavage	Distinct
Fracture	Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.
Crystal Habit：Massive - Granular - Common texture observed in granite and other igneous rock; Striated - Parallel lines on crystal surface or cleavage face.

Columbite, also called niobite, niobite-tantalite and columbate [(Fe, Mn)Nb₂O₆], is a black mineral group that is an ore of niobium. It has a submetallic luster and a high density and is a niobate of iron and manganese. This mineral group was first found in Haddam, USA. It forms a series with the tantalum-dominant analogue ferrotantalite and one with the manganese-dominant analogue manganocolumbite. The iron-rich member of the columbite group is ferrocolumbite. Some tin and tungsten may be present in the mineral. Yttrocolumbite is the yttrium-rich columbite with the formula (Y,U,Fe)(Nb,Ta)O₄. It is a radioactive mineral found in Mozambique.

Columbite has the same composition and crystal symmetry (orthorombic) as tantalite. In fact, the two are often grouped together as a semi-singular mineral series called columbite-tantalite or coltan in many mineral guides. However, tantalite has a much greater specific gravity than columbite, more than 8.0 compared to columbite's 5.2.

Columbite is also very similar to tapiolite. Those minerals have same chemical composition but different crystal symmetry: orthorhombic for columbite and tetragonal for tapiolite. The largest documented single crystal of columbite consisted of plates 6 millimetres (0.24 in) thick measuring 76 by 61 centimetres (30 × 24 in).