Columbite


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columbite

[kə′ləm‚bīt]
(mineralogy)
(Fe,Mn)(Cb,Ta)2O6 An 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.

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.

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Nigeria has arguably the largest Bitumen, Columbite and Tin deposits in the world today.
could include but is not limited to Chinese tungsten, Jamaican or Australian bauxite, African cocoa beans, Brazilian tantalite and columbite, and coffee from a range of foreign locations.
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Tantalo-niobates such as tantalite and columbite are ideally suited for U-Pb dating because of the potential to incorporate U (200-1000 ppm; Romer & Wright 1992; Kinny 2000) and, therefore, contain a significant radiogenic lead content.
The minerals identified included bastnaesite, yttrofluorite, yttrocerite, columbite, changbaiite, and kasolite.