Columbite

Columbite-(Fe)
General
Category	Oxide minerals
Chemical formula	Fe2+Nb2O6
Strunz classification	04.DB.35
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.
Crystal system	Orthorhombic, (2/m 2/m 2/m), SpaceGroup = Pcan
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	non-radioactive, non-fluorescent.
References	[1][2]

Columbite, also called niobite, niobite-tantalite and columbate [(Fe, Mn)(Nb, Ta)₂O₆], is a black mineral group that is an ore of niobium and tantalum. It has a submetallic luster and a high density and is a niobate of iron and manganese, containing tantalate of iron. This mineral group was first found in Haddam, USA. It forms a series with the tantalum-dominant analogue ferrotantalite and one with the manganese-dominant analogue manganocolumbite. The iron-rich member of the columbite group is ferrocolumbite. Some tin and tungsten may be present in the mineral. Yttrocolumbite is the yttrium-rich columbite with the formula (Y,U,Fe)(Nb,Ta)O₄. It is a radioactive mineral found in Mozambique.

Columbite has the same composition and crystal symmetry (orthorombic) as tantalite. 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.^[3]

Columbite is also very similar to tapiolite. Those minerals have same chemical composition but different crystal symmetry: orthorhombic for columbite and tetragonal for tapiolite.^[4] The largest documented single crystal of columbite consisted of plates 6 millimetres (0.24 in) thick measuring 76 by 61 centimetres (30 × 24 in).^[5]

See also

• Coltan
• List of minerals

References

1. ^ Columbite-(Fe) Mineral Data
2. ^ Columbite-(Fe) on Mindat.org
3. ^ mindat.org Tantalite
4. ^ P. Cerny et al. "The tantalite-tapiolite gap: natural assemblages versus experimental data" Canadian Mineralogist 30 (1992) 587 free download
5. ^ P. C. Rickwood (1981). "The largest crystals". American Mineralogist 66: 885–907. http://www.minsocam.org/ammin/AM66/AM66_885.pdf. 

This article about a specific oxide mineral is a stub. You can help Wikipedia by expanding it.v · Categories: Iron minerals Manganese minerals Niobium minerals Tantalum minerals Oxide minerals Orthorhombic minerals Oxide mineral stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем написать реферат Columbarium suzukii Columbella Look at other dictionaries: Columbite — Co*lum bite, n. [Cf. F. colombite. See {Columbium}.] (Min.) A mineral of a black color, submetallic luster, and high specific specific gravity. It is a niobate (or columbate) of iron and manganese, containing tantalate of iron; first found in New …   The Collaborative International Dictionary of English columbite — [kə lum′bīt΄] n. [ COLUMB(IUM) + ITE1] a black, orthorhombic mineral, (Fe,Mn)(Nb,Ta) 2O6, that is an ore of niobium and tantalum …   English World dictionary columbite — ● colombite ou columbite nom féminin (anglais columbite) Niobotantalate naturel de fer et de manganèse, utilisé comme minerai de niobium (ou colombium). ● colombite ou columbite (synonymes) nom féminin (anglais columbite) Niobotantalate naturel… …   Encyclopédie Universelle columbite — /keuh lum buyt/, n. a black, crystalline mineral, iron niobate, (Fe, Mn)Nb2O6, the principal ore of niobium, an end member of a series of solid solutions in which manganese and tantalum combine to form tantalite. [1795 1805; COLUMB(IUM) + ITE1] * …   Universalium columbite — kolumbitas statusas T sritis chemija apibrėžtis Mineralas. formulė (Fe,Mn)(Nb,Ta)₂O₆ atitikmenys: angl. columbite; niobite rus. колумбит; ниобит ryšiai: sinonimas – niobitas …   Chemijos terminų aiškinamasis žodynas columbite — noun Etymology: New Latin columbium Date: 1805 a black mineral consisting mostly of iron and niobium …   New Collegiate Dictionary columbite — noun A black mineral that is a mixed iron and manganese niobate and tantalate, and is the main ore of niobium and tantalum See Also: columbium …   Wiktionary columbite — co·lum·bì·te s.f. TS mineral. minerale raro di colore nero, costituito da ossido di ferro, manganese, niobio e tantalio, principale fonte di questi ultimi due metalli {{line}} {{/line}} DATA: 1892 …   Dizionario italiano columbite — pl.f. columbiti …   Dizionario dei sinonimi e contrari columbite — [kə lʌmbʌɪt] noun a black mineral consisting of an oxide of iron, manganese, niobium, and tantalum. Origin C19: from columbium + ite1 …   English new terms dictionary 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”