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Topic: Columbite

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	Columbite,Columbite Information,Columbite Uses,Columbite Suppliers
		Columbite is the most widespread niobium mineral and makes for an important ore of the industrially useful metal.
		Columbite is the more niobium rich end member and tantalite is the more tantalum rich end member.
		However the end members are recognized as distinct minerals although collectors have found this to be rather cumbersome and generally prefer columbite to the non-unique names of ferrocolumbite, manganocolumbite and magnocolumbite.
	www.mineralszone.com /minerals/columbite.html (331 words)

	Columbite: Columbite mineral information and data.
		When not prefixed the name Columbite usually refers to Ferrocolumbite.
		Columbite covers the series from Ferrocolumbite to Manganocolumbite.
		Romer, R.L. and Wright, J.E. (1992) U-Pb dating of columbites: a geochronologic tool to date magmatism and ore deposits.
	www.mindat.org /min-1112.html (395 words)

	[No title]
		By 1957 operations stopped after demand for columbite for the US strategic stockpile ceased, and no alternative market was found.
		This project was designed to attempt to establish the source of the columbite / tantalite, better define the extent of the deposits and also explore for other elements of commercial value.
		Results show columbite / tantalite occurrences with associated high rare earth, base metal, Mn, U and W concentrations are related to pegmatites in granites in an oval 10km wide area, broadly ringed by basaltic to doleritic intrusions.
	www.sdnp.org.gy /ggmc/morabisi.html (633 words)

	362 (Site not responding. Last check: 2007-09-10)
		Greater than 3 wt% Nb2O5 and >5 wt% Ta2O5 are required for columbite saturation in strongly peralkaline granitic melts (A.S.I. 0.55), whereas >1000 ppm Nb2O5 and >5000 ppm Ta2O5 required for saturation in subaluminous to peraluminous granitic melts.
		Columbite solubility is strongly dependent on temperature in subaluminous to peraluminous melts, e.g.
		If the data for the subaluminous composition are extrapolated to the crystallization conditions of pegmatites or highly evolved granite (600°C, 2 kbar), where columbite occurs as a magmatic mineral, and assuming a melt with 0.05 wt% MnO, 1400 ppm Ta or 330 ppm Nb are required for columibite saturation.
	www.esc.cam.ac.uk /Library/Journals/J.Conf.Abs./1/362.html (594 words)

	Niobium Summary
		Columbite and pyrochlore are not mined in the United States.
		Hatchett found niobium in columbite ore that was sent to England in the 1750s by John Winthrop, the first governor of Connecticut.
		There was a considerable amount of confusion about the difference between the closely-related niobium and tantalum that wasn't resolved until 1846 by Heinrich Rose and Jean Charles Galissard de Marignac, who rediscovered the element.
	www.bookrags.com /Niobium (2861 words)

	COLUMBITE - Online Information article about COLUMBITE
		Specimens in which the iron is largely replaced by manganese are known as manganocolumbite or manganotantalite, according as they contain more niobium or more tantalum.
		Columbite occurs as crystals and compact masses in See also:
		Dimorphous with columbite and tantalite are the tetragonal minerals tapiolite (= skogbolite) and mossite, so that the four See also:
	encyclopedia.jrank.org /CLI_COM/COLUMBITE.html (474 words)

	Tese de Mestrado de Luísa Paula Valente da Cruz
		The synthesis of PMN compounds by the conventional mixed oxide and columbite methods, allow the evaluation of the effect of various parameters in the process of the stabilization of the perovskite phase.
		The parameters studied in the mixing/grinding step were the sifting of the oxide precursors and the initial mixture, the reactivity of the raw materials and the grinding time.
		This study involves samples prepared by the columbite method with variable percentage of niobium oxide (V), and confirmed the influence of this oxide on the formation of pyrochlore phase.
	www.ipv.pt /ci/teses/pv_mest.htm (1197 words)

	It's Elemental - The Element Niobium
		The columbite sat in the museum's mineral collection for years until it was analyzed by Charles Hatchett in 1801.
		Hatchett could tell that there was an unknown element in the columbite, but he was not able to isolate it.
		Niobium was rediscovered and renamed by Heinrich Rose in 1844 when he produced two new acids, niobic acid and pelopic acid, from samples of columbite and tantalite.
	education.jlab.org /itselemental/ele041.html (361 words)

	Mobile Phones, Coltan and Civil War
		I'll attempt in this story to give a less depressing account and a more technical view on the circumstances of mining the mineral of Columbite-Tantalite found in the west of the Democratic Republic of Congo (DRC) as well as a little on Diamonds that are concentrated mainly in the south of DRC.
		Columbite and Tantalite are related minerals, in fact there is complete solid solution between both end members.
		Tantalum is used in alloys for strength and higher melting points, in glass to increase the index of refraction, and in surgical steel, as it is non-reactive and non-irritating to body tissues.
	www.geocities.com /rodneys_geology/Congo-Coltan.html (1042 words)

	Bayerisches Geoinstitut - Annual Report 2004 - The compressional behaviour of the columbite-group minerals along the ...
		Columbites (samples with Nb as the dominant B cation) and tantalites (samples with Ta as the dominant B cation) crystallise in the orthorhombic system, space group Pbcn, with an α-PbO
		Minerals of the columbite group show a wide range of degrees of order; complete order can be experimentally achieved by annealing at high temperature, whereas completely disordered samples have never been found or synthesized.
		The aim of this work is to study the high-pressure behaviour of the columbite-group minerals as a function of chemical composition and degree of order.
	www.bgi.uni-bayreuth.de /annual_report/2004/c_40.phtml (576 words)

	COLUMBITE (Iron Manganese Magnesium Niobium Tantalum Oxide)
		Also very flat tabular crystals often aggregated together in parallel or nearly parallel groups.
		Specific Gravity is approximately 5.0 to 5.3+ when near pure columbite (very heavy for non-metallic minerals).
		Other Characteristics: Some specimens may demonstrate weak magnetism.
	mineral.galleries.com /minerals/oxides/columbit/columbit.htm (471 words)

	Mineralogical Society of America
		Linnen, R.L. and Keppler, H. (1997) Columbite solubility in granitic melts: Consequences for the enrichment and fractionation of Nb and Ta in the Earth's crust: Contrib.
		This suggests that Nb or Ta is not strongly preferred in the columbite structure, rather that the composition of the melt controls the Nb/Ta ratio of the columbite-tantalite mineral that crystallizes from it.
		Linnen, R.L. and Keppler, H., 1997, Columbite solubility in granitic melts: Consequences for the enrichment and fractionation of Nb and Ta in the Earth' s crust: Contrib.
	www.minsocam.org /MSA/Special/Pig/PIG_CQ/PIG_CQ_Kjellman.html (966 words)

	SME--VIRTUAL ATLAS OF OPAQUE AND ORE MINERALS
		Although the reflectance of zircon is lower than columbite, it is higher than the silicates.
		Two columbite crystals (brown, centre left and right) have small zircon crystals (medium grey) growing around them.
		Columbite (brown-grey, centre) is enclosed within a higher reflectance rutile (light grey, with fractures).
	www.smenet.org /opaque-ore/Plate16.htm (524 words)

	Case
		The prospect in the middle of the three older quarries was exposed in the early 1980s and large (up to a foot across!) hexagonal beryls lined the contact between the quartz core and the thin pegmatite zone next to the surrounding gneiss.
		Columbites range from very beautiful, elongated micro-crystals to large, crude crystals up to 1 1/2 inches long.
		The golden beryl is associated with smoky quartz, microcline feldspar, bismutite, bismite, and columbite.
	www.lmscc.org /case.htm (4368 words)

	Gem, Rock, and Mineral Postage Stamps Featuring Columbite-tantalite (Site not responding. Last check: 2007-09-10)
		Additional Notes: Columbite forms a series with the mineral tantalite.
		Columbite is the end-member with more niobium (at one time niobium was called columbium, hence the name columbite); tantalite is the end-member with more tantalum.
		Since columbite and tantalite exhibit very similar properties and since a detailed chemical analysis is generally needed to distinguish the two minerals, specimens from the series are typically referred to as "columbite-tantalite."
	stampmin.home.att.net /columbite-tantalite.htm (106 words)

	MBMG SP 28 - MINERAL AND WATER RESOURCES OF MONTANA: Minerals M-So
		Columbite, the commonest ore mineral of niobium (columbium) is a niobate-tantalate of iron and manganese.
		Columbite is usually recognized by its iron-fl, commonly iridescent color.
		In this deposit columbite is associated with euxenite and fersmite, along with the rare-earth minerals ancylite, allanite, and monazite.
	www.mbmg.mtech.edu /sp28/minm-sod.htm (10951 words)

	Sierra Leone Government warns illicit Coltan miners
		Recent investigations have revealed illicit mining of Columbite and that a large-scale illicit mining operation of the said mineral is being carried out under a prospecting licence for gold and another group involved in a similar illicit operation is now known to Government.
		In the Diang Chiefdom, Koinadugu District, similar illicit mining activities have been going on and Government has instructed the police to stop all such illicit activities until investigations are concluded and appropriate legal steps taken to pave the way for normal and legal operations to restart.
		This will apply both in the Northern and Southern Provinces where illicit mining of COLUMBITE and gold has been reported to be alarming.
	news.sl /drwebsite/publish/printer_2005848.shtml (500 words)

	Amazon.com: columbite (Site not responding. Last check: 2007-09-10)
		Ixiolite -- a columbite substructure (Research report / Dept. of Mines and Technical Surveys, Mines Branch) by Ernest H Nickel (Unknown Binding - 1964)
		Notes on lawsonite, columbite, beryl, barite, and calcite (University of California publications.
		Columbite (Mineral resources pamphlet / Guyana Geology and Mines Commission) by Karen Livan (Unknown Binding - 1980)
	www.amazon.com /s?ie=UTF8&keywords=columbite&tag=lexico&index=blended&link_code=qs&page=1 (772 words)

	Interresource - Columbite
		Conducted for the part of the deposit geological exploration, which gives an estimates of the deposit top side in excess of 7 thousand tons of pentoxides (11 thousand tons of concentrate), with potential for the increase of this volume in the process of lower levels development.
		At the first stage of the project it is offered to reorganize industrial columbite mining project with achievement of the production level of 40t to 60t of columbite concentrate per month.
		We are inviting the technical partner to install modern equipment and reach acceptable mining level with a perspective of further columbite processing directly in Nigeria.
	interresource.info /columbite_e.htm (1033 words)

	Author Auteur
		(i) At Praivá (Slovak Republic), niobian rutile, associated with titanian columbite and a Fe3+NbO4-rich titanian ixiolite, displays very fine (1 to 3 µm) lamellar exsolution of niobian armalcolite to pseudobrookite (6 to 10 wt.% Nb2O5, 0.5 to 5.5 wt.% Ta2O5), and later aggregates of niobian ilmenite, ilmenite and titanian hematite.
		In spatial progression from these aggregates, exsolution in the primary niobian rutile advances into progressively coarser intergrowth of rutile and columbite, both displaying progressively lower degrees of mutual solid solution.
		Zirconium is rarely analyzed for in minerals of the broader columbite family, and no data are available for hafnium.
	www.ggl.ulaval.ca /cgi-bin/consultau.cgi?616&617& (813 words)

	Collections 1 New Find Minerals Rocks Crystals Gems Fossils Specimens for the Professional and Hobbie Geology Collector
		A large single columbite nucleating along an albite base, with coarse microcline along one side of the crystal.
		The lease on this columbite property in Australia is available for sale and offers have been received.
		An upright columbite crystal with a dull lustre and embayed faces, the termination is complex, with two terminations visible.
	newfindminerals.tripod.com /nfm1.htm (1073 words)

	The Curious Case of Columbium
		He was elected a Fellow of the Royal Society in 1797, which is a measure of the esteem in which he was held by his fellow scientists.
		Both columbite and tantalite were analysed by William Wollaston in 1809 (after Hatchett had effectively given up science and taken over his father's coach-building business following the latter's death).
		Wollaston was confused by the similarity in the physical and chemical properties of the two elements and he thought they were the same i.e.
	www.ul.ie /~childsp/CinA/Issue65/TOC43_Columbian.htm (1351 words)

	New Find Minerals Rocks Crystals Gems Fossils Jewels Specimens
		From this pegmatite we have gemmy green beryl specimens and beryl rough.
		We will be featuring an article on our columbite mining operation soon.
		Typically columbite is found on the extremities of intrusions while tantalite is found deeper within the intrusive body.
	newfindminerals.tripod.com (492 words)

	Svecofennian granitic pegmatites (1.86-1.79 Ga) and quartz monzonite (1.87 Ga) ...
		1.80 Ga, U-Pb columbite age) that contain accessory columbite and fluorite, and form a unique subtype among the beryl pegmatites.
		1.80 Ga, U-Pb columbite ages) are the richest in rare minerals such as columbite, cassiterite, spodumene and lepidolite.
		The columbites dated differ in chemical composition from ferrocolumbite to mangano-columbite, and there is minor variation in the contents of Ti and W. Older rare-earth-element (REE)-pegmatites (ca.
	www.gsf.fi /info/sp30abs.html (1064 words)

	Coltan / Columbite-Tantalite from READE
		Coltan, columbite- tantalite,, ferrotantalita, ferrocolumbite, ferrotantalite, manganocolumbite, manganotantalite, stibiocolumbite, stibiotantalite, Coltan, columbite- tantalite,, ferrotantalita, ferrocolumbite, ferrotantalite, manganocolumbite, manganotantalite, stibiocolumbite, stibiotantalite
		Coltan, columbite- tantalite,, ferrotantalita, ferrocolumbite, ferrotantalite, manganocolumbite, manganotantalite, stibiocolumbite, stibiotantalite
		Coltan, columbite- tantalite,, ferrotantalita, ferrocolumbite, ferrotantalite, manganocolumbite, manganotantalite, stibiocolumbite, stibiotantalite, Coltan, columbite- tantalite,, ferrotantalita, ferrocolumbite, ferrotantalite, manganocolumbite, manganotantalite, stibiocolumbite, stibiotantalite, Coltan, columbite- tantalite,, ferrotantalita, ferrocolumbite, ferrotantalite, manganocolumbite, manganotantalite, stibiocolumbite, stibiotantalite, Coltan, columbite- tantalite,, ferrotantalita, ferrocolumbite, ferrotantalite, manganocolumbite, manganotantalite, stibiocolumbite, stibiotantalite
	www.reade.com /Products/Minerals_and_Ores/coltan_columbite-tantalite.html (325 words)

	The Arkenstone: Fine Mineral Specimens (Site not responding. Last check: 2007-09-10)
		A sharp and lustrous 4 x 4.5 x 3 cm fan-shaped radial sheaf of wide tabular columbite crystals, with minor muscovite and albite.
		It features a sharp 1 cm mirror-bright lustrous columbite crystal perched on a miniature-sized pegmatite matrix of smoky quartz and muscovite.
		John Caswell (catalog #1511) acquired this historic specimen from the Newberry collection in 1878; more recently, this specimen was acquired by me in 2001 from Steve Chamberlain, who received it from Ron Bentley in 1980.
	www.irocks.com /jarnot.html (319 words)

	The Canadian Mineralogist
		Les minéraux du groupe de la columbite provenant des pegmatites du sous-type à spodumène entre Salta et San Luis montrent une large variation et des tracés évolutifs divers parmi les différents massifs.
		La composition des minéraux du groupe de la columbite des pegmatites à béryl post-orogéniques de la suite de Punilla correspond à la ferrocolumbite légèrement enrichie en éléments traces à champ électrostatique élevé.
		Mots clés : minéraux du groupe de la columbite, niobium, tantalum, géochimie, degré d’ordre, pegmatites enrichies en éléments rares, chaînes Pampéennes, Argentine.
	pubs.nrc-cnrc.gc.ca /mineral/tcm-64544-3.html (539 words)

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