Editing Group 4 element (section)

==Occurrence==
[[Image:HeavyMineralsBeachSand.jpg|right|thumb|Heavy minerals (dark) in a quartz beach sand ([[Chennai]], India).]]
The abundance of the group 4 metals decreases with increase of atomic mass. Titanium is the seventh most abundant metal in Earth's crust and has an abundance of 6320&nbsp;ppm, while zirconium has an abundance of 162&nbsp;ppm and hafnium has only an abundance of 3 ppm.<ref>{{cite web|url = http://www.webelements.com/periodicity/abundance_crust/|title = Abundance in Earth's Crust|publisher = WebElements.com|access-date = 2007-04-14|archive-url = https://web.archive.org/web/20080523082920/http://www.webelements.com/periodicity/abundance_crust/|archive-date = 2008-05-23|url-status = dead}}</ref>

All three stable elements occur in [[heavy mineral sands ore deposits]], which are [[placer deposit]]s formed, most usually in [[beach]] environments, by concentration due to the [[specific gravity]] of the mineral grains of erosion material from [[mafic]] and [[ultramafic rock]]. The titanium minerals are mostly [[anatase]] and [[rutile]], and zirconium occurs in the mineral [[zircon]]. Because of the chemical similarity, up to 5% of the zirconium in zircon is replaced by hafnium. The largest producers of the group 4 elements are [[Australia]], [[South Africa]] and [[Canada]].<ref>{{cite web|url = http://www.alkane.com.au/projects/nsw/dubbo/DZP%20Summary%20June07.pdf|title = Dubbo Zirconia Project Fact Sheet|date = June 2007|publisher = Alkane Resources Limited|access-date = 2008-09-10|archive-url = https://web.archive.org/web/20080228054038/http://www.alkane.com.au/projects/nsw/dubbo/DZP%20Summary%20June07.pdf|archive-date = 2008-02-28|url-status = dead}}</ref><ref name="usgs2008">{{cite journal| title = Zirconium and Hafnium| journal = Mineral Commodity Summaries| pages = 192–193| publisher = US Geological Survey|date=January 2008| url = http://minerals.usgs.gov/minerals/pubs/commodity/zirconium/mcs-2008-zirco.pdf| access-date = 2008-02-24}}</ref><ref>{{cite web|last=Callaghan|first=R.|title=Zirconium and Hafnium Statistics and Information|publisher=US Geological Survey|date=2008-02-21|url=http://minerals.usgs.gov/minerals/pubs/commodity/zirconium/|access-date=2008-02-24}}</ref><ref name="usgypTi2009">{{cite web|title = Minerals Yearbook Commodity Summaries 2009: Titanium |publisher = US Geological Survey|date=May 2009|url = http://minerals.usgs.gov/minerals/pubs/commodity/titanium/myb1-2007-titan.pdf| access-date = 2008-02-24}}</ref><ref name="usgcomTi2009">{{cite web|last = Gambogi|first= Joseph|title = Titanium and Titanium dioxide Statistics and Information|publisher=US Geological Survey|date=January 2009|url=http://minerals.usgs.gov/minerals/pubs/commodity/titanium/mcs-2009-titan.pdf|access-date = 2008-02-24}}</ref>