Editing Niobium (section)

====Numismatics====
Niobium is used as a precious metal in commemorative coins, often with [[silver]] or [[gold]]. For example, Austria produced a series of silver niobium [[euro]] coins starting in 2003; the colour in these coins is created by the [[diffraction]] of light by a thin anodized oxide layer.<ref>{{cite journal|doi = 10.1016/j.ijrmhm.2005.10.008|journal = International Journal of Refractory Metals and Hard Materials|volume = 24|issue = 4|date = 2006|pages = 275–282|title = Niobium as mint metal: Production–properties–processing|first =Robert|last = Grill|author2=Gnadenberge, Alfred }}</ref> In 2012, ten coins are available showing a broad variety of colours in the centre of the coin: blue, green, brown, purple, violet, or yellow. Two more examples are the 2004 Austrian €25 [[Euro gold and silver commemorative coins (Austria)#2004 coinage|150-Year Semmering Alpine Railway commemorative coin]],<ref>{{cite web|url =http://austrian-mint.at/bimetallmuenzen?l=en&muenzeSubTypeId=113&muenzeId=217|archive-url =https://web.archive.org/web/20110721053534/http://austrian-mint.at/bimetallmuenzen?l=en&muenzeSubTypeId=113&muenzeId=217|archive-date=21 July 2011|title = 25 Euro – 150 Years Semmering Alpine Railway (2004)|access-date=4 November 2008|publisher = [[Austrian Mint]]}}</ref> and the 2006 Austrian €25 [[Euro gold and silver commemorative coins (Austria)#2006 coinage|European Satellite Navigation commemorative coin]].<ref>{{cite web|url =http://www.austrian-mint.at/cms/download.php?downloadId=131|archive-url =https://web.archive.org/web/20110720002739/http://www.austrian-mint.at/cms/download.php?downloadId=131|archive-date=20 July 2011|title = 150 Jahre Semmeringbahn|access-date=4 September 2008| publisher = [[Austrian Mint]]| language=de}}</ref> The Austrian mint produced for Latvia a similar series of coins starting in 2004,<ref>{{cite web|url =http://www.bank.lv/eng/main/all/lvnaud/jubmon/nmp/time/|archive-url =https://web.archive.org/web/20080109033431/http://www.bank.lv/eng/main/all/lvnaud/jubmon/nmp/time/ |archive-date=9 January 2008 |title = Neraža – mēs nevarējām atrast meklēto lapu!|language=lv|access-date=19 September 2008|publisher = Bank of Latvia}}</ref> with one following in 2007.<ref>{{cite web|url = http://www.bank.lv/eng/main/all/lvnaud/jubmon/nmp/time2/|archive-url = https://web.archive.org/web/20090522101540/http://www.bank.lv/eng/main/all/lvnaud/jubmon/nmp/time2/|archive-date=22 May 2009|title = Neraža – mēs nevarējām atrast meklēto lapu!|language=lv|access-date=19 September 2008|publisher = Bank of Latvia}}</ref> In 2011, the Royal Canadian Mint started production of a $5 [[sterling silver]] and niobium coin named ''Hunter's Moon''<ref>{{Cite web|url=http://www.mint.ca/store/coin/5-sterling-silver-and-niobium-coin-hunters-moon-2011-prod1110013|title=$5 Sterling Silver and Niobium Coin – Hunter's Moon (2011)|publisher=Royal Canadian Mint|access-date=1 February 2012|archive-date=25 February 2014|archive-url=https://web.archive.org/web/20140225232038/http://www.mint.ca/store/coin/5-sterling-silver-and-niobium-coin-hunters-moon-2011-prod1110013|url-status=live}}</ref> in which the niobium was selectively oxidized, thus creating unique finishes where no two coins are exactly alike.

[[File:2004 Austria 25 Euro 150 Years Semmering Alpine Railway front.jpg|thumb|center|A 150 Years [[Semmering railway|Semmering Alpine Railway]] Coin made of niobium and silver |alt=Coin with a dark green center and a silvery outer rim. The rim reads: Republik Österreich 25 Euro. The centere shows electric and a steam driven locomotive]]