Editing Niobium (section)

===Occurrence===
{{see also|Category:Niobium minerals}}
Niobium is estimated to be the [[Abundance of elements in Earth's crust|33rd most abundant element in the Earth's crust]], at 20&nbsp;[[Parts per million|ppm]].<ref>{{cite book|title = Nature's Building Blocks: An A-Z Guide to the Elements|last = Emsley|first = John|publisher = Oxford University Press|date = 2001|location = Oxford, England|isbn = 978-0-19-850340-8|chapter = Niobium|pages = [https://archive.org/details/naturesbuildingb0000emsl/page/283 283–286]|chapter-url = https://archive.org/details/naturesbuildingb0000emsl/page/283}}</ref> Some believe that the abundance on Earth is much greater, and that the element's high density has concentrated it in Earth's core.<ref name="patel" /> The free element is not found in nature, but niobium occurs in combination with other elements in minerals.<ref name="Nowak">{{cite journal|title=Niobium Compounds: Preparation, Characterization, and Application in Heterogeneous Catalysis|author=Nowak, Izabela|author2=Ziolek, Maria|journal=Chemical Reviews|date=1999|volume=99|issue=12|pages=3603–3624|doi=10.1021/cr9800208|pmid=11849031}}</ref> Minerals that contain niobium often also contain tantalum. Examples include [[Ferrocolumbite|columbite]] ({{chem2|(Fe,Mn)Nb2O6}}) and [[coltan|columbite–tantalite]] (or ''coltan'', {{chem2|(Fe,Mn)(Ta,Nb)2O6}}).<ref name="ICE" /> Columbite–tantalite minerals (the most common species being columbite-(Fe) and tantalite-(Fe), where "-(Fe)" is the Levinson suffix indicating the prevalence of iron over other elements such as manganese<ref>{{Cite web|url=https://www.mindat.org/min-1514.html|title=Columbite-(Fe): Mineral information, data and localities.|website=www.mindat.org|access-date=6 October 2018|archive-date=18 March 2017|archive-url=https://web.archive.org/web/20170318085151/https://www.mindat.org/min-1514.html|url-status=live}}</ref><ref>{{Cite web|url=https://www.mindat.org/min-1530.html|title=Tantalite-(Fe): Mineral information, data and localities.|website=www.mindat.org|access-date=6 October 2018|archive-date=6 November 2018|archive-url=https://web.archive.org/web/20181106004948/https://www.mindat.org/min-1530.html|url-status=live}}</ref><ref name="Burke">{{cite journal |journal=Elements |last1=Burke |first1=Ernst A.J. |title=The use of suffixes in mineral names |url=http://elementsmagazine.org/archives/e4_2/e4_2_dep_mineralmatters.pdf |date=2008 |volume=4 |issue=2 |page=96 |access-date=7 December 2019 |archive-date=19 December 2019 |archive-url=https://web.archive.org/web/20191219014458/http://elementsmagazine.org/archives/e4_2/e4_2_dep_mineralmatters.pdf |url-status=live }}</ref><ref name="nrmima.nrm.se">{{Cite web|url=http://nrmima.nrm.se/|title=CNMNC|website=nrmima.nrm.se|access-date=6 October 2018|archive-url=https://web.archive.org/web/20190810195707/http://nrmima.nrm.se//|archive-date=10 August 2019|url-status=dead}}</ref>) that are most usually found as accessory minerals in [[pegmatite]] intrusions, and in [[alkali]]ne [[intrusive rock]]s. Less common are the niobates of [[calcium]], [[uranium]], [[thorium]] and the [[rare earth element]]s. Examples of such niobates are [[pyrochlore]] ({{chem2|(Na,Ca)2Nb2O6(OH,F)}}) (now a group name, with a relatively common example being, e.g., fluorcalciopyrochlore<ref name="Burke" /><ref name="nrmima.nrm.se" /><ref>{{Cite web|url=https://www.mindat.org/min-3316.html|title=Pyrochlore Group: Mineral information, data and localities.|website=www.mindat.org|access-date=6 October 2018|archive-date=19 June 2018|archive-url=https://web.archive.org/web/20180619113047/https://www.mindat.org/min-3316.html|url-status=live}}</ref><ref>{{Cite web|url=https://www.mindat.org/min-40341.html|title=Fluorcalciopyrochlore: Mineral information, data and localities.|website=www.mindat.org|access-date=6 October 2018|archive-date=28 September 2018|archive-url=https://web.archive.org/web/20180928043940/https://www.mindat.org/min-40341.html|url-status=live}}</ref><ref>{{cite journal |url=http://rruff.info/uploads/AM62_403.pdf |title=Classification and nomenclatureof the pyrochlore group |last=Hogarth |first=D. D. |date=1977 |journal=American Mineralogist |volume=62 |pages=403–410 |archive-url=https://web.archive.org/web/20181105030236/http://rruff.info/uploads/AM62_403.pdf |archive-date=5 November 2018}}</ref>) and [[euxenite]] (correctly named euxenite-(Y)<ref name="Burke" /><ref name="nrmima.nrm.se" /><ref>{{Cite web|url=https://www.mindat.org/min-1425.html|title=Euxenite-(Y): Mineral information, data and localities.|website=www.mindat.org|access-date=6 October 2018|archive-date=7 October 2018|archive-url=https://web.archive.org/web/20181007040042/https://www.mindat.org/min-1425.html|url-status=live}}</ref>) ({{chem2|(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6}}). These large deposits of niobium have been found associated with [[carbonatite]]s [[carbonate minerals|(carbonate]]-[[silicate]] [[igneous rocks]]) and as a constituent of pyrochlore.<ref name="Pyrochlore">{{cite journal|title = Geochemical alteration of pyrochlore group minerals: Pyrochlore subgroup|date = 1995|first = Gregory R.|last = Lumpkin|author2 = Ewing, Rodney C.|journal = American Mineralogist|url = http://www.minsocam.org/msa/AmMin/TOC/Articles_Free/1995/Lumpkin_p732-743_95.pdf|volume = 80|issue = 7–8|pages = 732–743|bibcode = 1995AmMin..80..732L|doi = 10.2138/am-1995-7-810|s2cid = 201657534|access-date = 14 October 2008|archive-date = 17 December 2008|archive-url = https://web.archive.org/web/20081217100545/http://www.minsocam.org/msa/AmMin/TOC/Articles_Free/1995/Lumpkin_p732-743_95.pdf|url-status = live}}</ref> <!--http://minmag.geoscienceworld.org/cgi/content/abstract/64/4/683 -->

The three largest currently mined deposits of pyrochlore, two in Brazil and one in Canada, were found in the 1950s, and are still the major producers of niobium mineral concentrates.<ref name="Gupta" /> The largest deposit is hosted within a [[carbonatite]] [[Igneous intrusion|intrusion]] in [[Araxá]], state of [[Minas Gerais]], Brazil, owned by CBMM ([[Companhia Brasileira de Metalurgia e Mineração]]); the other active Brazilian deposit is located near [[Catalão]], state of [[Goiás]], and owned by [[China Molybdenum]], also hosted within a carbonatite intrusion.<ref name="tesla" /> Together, those two mines produce about 88% of the world's supply.<ref name="g1">{{cite news |last=Alvarenga |first=Darlan |url=http://g1.globo.com/economia/negocios/noticia/2013/04/monopolio-brasileiro-do-niobio-gera-cobica-mundial-controversia-e-mitos.html |title='Monopólio' brasileiro do nióbio gera cobiça mundial, controvérsia e mitos |language=pt |trans-title=Brazilian niobium 'monopoly' brings about the world's greed, controversy, and myths |work=[[G1 (website)|G1]] |location=São Paulo |date=9 April 2013 |access-date=23 May 2016 |archive-date=29 May 2016 |archive-url=https://web.archive.org/web/20160529175614/http://g1.globo.com/economia/negocios/noticia/2013/04/monopolio-brasileiro-do-niobio-gera-cobica-mundial-controversia-e-mitos.html |url-status=live }}</ref> Brazil also has a large but still unexploited deposit near [[São Gabriel da Cachoeira]], state of [[Amazonas (Brazilian state)|Amazonas]], as well as a few smaller deposits, notably in the state of [[Roraima]].<ref name="g1" /><ref name="rio negro">{{cite journal|last1=Siqueira-Gay|first1=Juliana |last2=Sánchez| first2=Luis E.|title =Keep the Amazon niobium in the ground|journal= Environmental Science & Policy|volume=111|year= 2020|pages= 1–6|issn=1462-9011|doi =10.1016/j.envsci.2020.05.012 |bibcode=2020ESPol.111....1S |s2cid=219469278 }}</ref>

The third largest producer of niobium is the carbonatite-hosted [[Niobec]] mine, in [[Saint-Honoré, Quebec|Saint-Honoré]], near [[Chicoutimi]], [[Quebec]], Canada, owned by Magris Resources.<ref name="niobec-magris">{{cite press release |url=http://niobec.com/en/2015/01/magris-resources-officially-owner-of-niobec/ |title=Magris Resources, officially owner of Niobec |publisher=Niobec |date=23 January 2015 |access-date=23 May 2016 |archive-date=5 June 2016 |archive-url=https://web.archive.org/web/20160605092511/http://niobec.com/en/2015/01/magris-resources-officially-owner-of-niobec/ |url-status=live }}</ref> It produces between 7% and 10% of the world's supply.<ref name="tesla">{{cite web|url = http://tesla.desy.de/new_pages/TESLA_Reports/2001/pdf_files/tesla2001-27.pdf|title = Niob für TESLA|access-date = 2 September 2008|first = J.|last = Kouptsidis|author2 = Peters, F.|author3 = Proch, D.|author4 = Singer, W.|publisher = Deutsches Elektronen-Synchrotron DESY|language = de|url-status = dead|archive-url = https://web.archive.org/web/20081217100548/http://tesla.desy.de/new_pages/TESLA_Reports/2001/pdf_files/tesla2001-27.pdf|archive-date = 17 December 2008|df = dmy-all}}</ref><ref name="g1" />