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(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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(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.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Brusset, "Normal coordinate analysis for Ca[Nb.sub.2][O.sub.6] of columbite structure," The Journal of Chemical Physics, vol.
The eastern part towards the center area supports the previous reports on the existence of geological structures (such as mica, feldspar, beryl, tantalite, tourmaline, and columbite) in this part of the Ibadan schist belt [15, 23].
Apart form oil and gas, Nigeria's other minerals include tin, columbite, coal and limestone but none of these were exported in large quantities.
Project unit 98-016: combined U-Pb columbite and [sup.40]Ar/[sup.39]Ar mica ages from rare-element pegmatites, Superior Province of northwestern Ontario.
Due to the higher solubility of tantalite relative to that of columbite in peraluminous granitic magmas [3, 65], one can expect a late Ta enrichment relative to Nb in the residual melt and thus a high Ta/Nb ratio in the exsolved magmatic fluid, despite low partition coefficients for Nb and Ta between an aqueous fluid and silicate melt in granitic systems ([D.sup.fluid-melt] [Ta] < [D.sup.fluid-melt] [Nb] < 0.1) [3, 66-68].
Nigeria is also endowed with variety of solid minerals ranging from coal, cassiterite and columbite in the southern region to limestone, iron ore, tin and marble in the northern region.
In diversifying its economy away from its dependence on oil, Nigeria's underexploited mining sector had resources of iron ore, tine, columbite, tantalite, gypsum, cola, gold, nickel, lead and uranium to exploit.
Oil, natural gas, petroleum, tin, columbite, iron, coal, limestone, lead, zinc, arable land, gold, chromium, antimony, manganese, nickel, phosphates, uranium, gem diamonds, platinum, copper, vanadium, salt, asbestos, lithium, cobalt, emeralds, silver, hydropower, clay, cassiterite (tin ore), forests, quarry, talc, cadmium, fish, titanium, tantalum, graphite, bauxite, chromite, quartz, tar sands, semiprecious stones, mica, water, soda ash, potash, feldspar, gypsum, timber, natron, kaolin, industrial diamonds, germanium, radium, marble, basalt rock, rubber, rare earth oxides, peat, geothermal resources, rubies, fluorspar, garnets, wolframite (tungsten ore), methane, copra, cinnamon trees, tungsten, gemstones, [wildlife].
There is another rare ore that one newspaper, England's The Independent, says "has joined the rogues' gallery of African subsoil resources fuelling wars on the ground." It's coltan, short for the minerals it contains - columbite and tantalite - and it's a key component in the manufacture of mobile phones and other electronic equipment: it was a low coltan supply that led to a shortage of PlayStation2 platforms in 2000.
The Flotinor collectors have proved successful for the flotation of non-sulphidic ores and industrial minerals such as cassiterite, columbite, wolframite, scheelite, barite, fluorite, heavy minerals from glass sands and particularly for apatite.