Columbite

Columbite
Columbite
General
Category	Oxide minerals
Formula; (repeating unit)	(FeII,MnII)Nb2O6, or in oxide formula (FeII,MnII)O·Nb2O5
IMA symbol	Clb
Strunz classification	4.DB.35
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) ; H-M symbol: (2/m 2/m 2/m)
Space group	Pbcn
Identification
Color	Black, brownish black.
Crystal habit	Massive – Granular – Common texture observed in granite and other igneous rock; Striated - Parallel lines on crystal surface or cleavage face.
Cleavage	[010] Distinct
Fracture	Sub Conchoidal: Fractures developed in brittle materials characterized by semi-curving surfaces.
Mohs scale hardness	6
Luster	Sub-metallic
Streak	Blackish brown
Specific gravity	5.3–7.3, Average = 6.3
Optical properties	Biaxial (+), b = 2.29–2.4
Other characteristics	Radioactive, non-fluorescent.
References

Columbite, also called niobite, niobite-tantalite and columbate, with a general chemical formula of (Fe^II,Mn^II)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.

^ 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.
^ Mineralienatlas
^ Columbite-(Fe) Mineral Data
^ Columbite-(Fe) on Mindat.org
^ 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.
^ 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.
^ mindat.org Tantalite
^ P. Cerny et al. "The tantalite-tapiolite gap: natural assemblages versus experimental data" Canadian Mineralogist 30 (1992) 587 free download
^ P. C. Rickwood (1981). "The largest crystals" (PDF). American Mineralogist. 66: 885–907.
^ "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.

[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

[Mindat-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] t.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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