Columbite (redirected from Ferrocolumbite)

columbite [kə′ləm‚bīt]

(mineralogy)

(Fe,Mn)(Cb,Ta)₂O₆An iron-black mineral with a submetallic luster that crystallizes in the orthorhombic system; the chief ore mineral of niobium (columbium); hardness is 6 on Mohs scale, and specific gravity is 5.4-6.5. Also known as dianite; greenlandite; niobite.

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Columbite 

(from Latin columbium, an alternate name for niobium), a mineral of the columbite-tantalite group, combining complex oxides of the AB₂O₆ type and forming the isomorphic series FeNb₂O₆—MnNb₂O₆ (columbite proper) and FeTa₂O₆—MnTa₂O₆ (tantalite). The columbites also include members of isomorphic series in which niobium (in weight percent) predominates over tantalum.

The varieties of columbite include tantalocolumbite (20–40 percent Ta₂O₅), ferrocolumbite (FeO : MnO > 3 : 1), manganocolumbite (MnO : FeO > 3:1), magnesiocolumbite (FeO < MgO > MnO), and ixiolite (to 13 percent SnO₂). In addition to the basic components, columbite almost always contains admixtures of titanium, tungsten, rare earth elements, uranium, thorium, and zirconium. Columbite crystallizes in the rhombic system. Its structure is based on the closest possible hexagonal (double-layered) packing of oxygen atoms, in the alternating layers of which the octahedral spaces are occupied in turn by (Nb, Ta) and (Fe, Mn). Columbite crystals are short prismatic, thin tabular, or tabular. They are black, brownish black, or, less often, reddish brown (manganocolumbites). The hardness of columbite is 6.0 on the mineralogical scale; the density, 5,150–6,350 kg per cu m (tantalocolumbites). Genetically, columbite is related to the quartz-bearing subalkaline syenites and the acidic alaskites, biotites, and binary granites, and particularly, to their pegmatitic and postmagmatic pneumatolytic and hydrothermal derivatives. Columbite is a source of niobium.