Back Kolumbiet Afrikaans كولومبيت Arabic Grup de la columbita Catalan Columbit German Κολουμπίτης Greek Columbita Spanish کلومبیت Persian Columbite French Columbite Hausa קולומביט HE

Columbite

Columbite
General
CategoryOxide minerals
Formula
(repeating unit)		(FeII,MnII)Nb2O6, or in oxide formula (FeII,MnII)O·Nb2O5
IMA symbolClb[1]
Strunz classification4.DB.35
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPbcn
Identification
ColorBlack, brownish black.
Crystal habitMassive – Granular – Common texture observed in granite and other igneous rock; Striated - Parallel lines on crystal surface or cleavage face.
Cleavage[010] Distinct
FractureSub Conchoidal: Fractures developed in brittle materials characterized by semi-curving surfaces.
Mohs scale hardness6
LusterSub-metallic
StreakBlackish brown
Specific gravity5.3–7.3, Average = 6.3
Optical propertiesBiaxial (+), b = 2.29–2.4
Other characteristics Radioactive, non-fluorescent.
References[2][3][4] [5]

Columbite, also called niobite, niobite-tantalite and columbate, with a general chemical formula of (FeII,MnII)Nb2O6, is a black mineral group that is an ore of niobium. It has a submetallic luster, a high density, and is a niobate of iron and manganese. Niobite has many applications in areospace, construction and the medical industry. Dating columbite minerals is primarily completed by uranium lead (U-Pb) dating, a slow process.

Columbite has the same composition and crystal symmetry (orthorhombic) as tantalite.[6] 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.[7] The formation of columbite depends on the concentrations of metals present that affect the crystalline structure of the mineral and the environmental impact.

Columbite is a polymorph of tapiolite; they have the same chemical composition but different crystal symmetry: orthorhombic for columbite and tetragonal for tapiolite.[8] The largest documented single crystal of columbite consisted of plates 6 mm (0.24 in) thick measuring 76 cm × 61 cm (30 in × 24 in).[9]

Columbite contains varying amounts of thorium and uranium, making it radioactive.[10] Coltan, a tantalum dominate species of columbite, is often mined by artisan and small scale miners with risks to the environment and human health due to unregulated working conditions.

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Mineralienatlas
  3. ^ Columbite-(Fe) Mineral Data
  4. ^ Columbite-(Fe) on Mindat.org
  5. ^ Dampare, S. B.; Nyarko, B. J. B.; Osae, S.; Akaho, E. H. K.; Asiedu, D. K.; Serfor-Armah, Y.; Nude, P. (2005). "Simultaneous determination of tantalum, niobium, thorium and uranium in placer columbite-tantalite deposits from the Akim Oda District of Ghana by epithermal instrumental neutron activation analysis". Journal of Radioanalytical and Nuclear Chemistry. 265: 53–59. doi:10.1007/s10967-005-0860-0. S2CID 97891922.
  6. ^ Chukanov, Nikita V.; Pasero, Marco; Aksenov, Sergey M.; Britvin, Sergey N.; Zubkova, Natalia V.; Yike, Li; Witzke, Thomas (2022-09-08). "Columbite supergroup of minerals: nomenclature and classification". Mineralogical Magazine. 87 (1): 18–33. doi:10.1180/mgm.2022.105. ISSN 0026-461X. S2CID 252172669.
  7. ^ mindat.org Tantalite
  8. ^ P. Cerny et al. "The tantalite-tapiolite gap: natural assemblages versus experimental data" Canadian Mineralogist 30 (1992) 587 free download
  9. ^ P. C. Rickwood (1981). "The largest crystals" (PDF). American Mineralogist. 66: 885–907.
  10. ^ "Simultaneous determination of tantalum, niobium, thorium and uranium in placer columbite-tantalite deposits from the Akim Oda District of Ghana by epithermal instrumental neutron activation analysis". Retrieved 2021-02-02.

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