Editing Ruthenium (section)

=== Occurrence ===
{{See also|Category:Ruthenium minerals}}
Ruthenium is found in about 100&nbsp;[[parts per trillion]] in the Earth's crust, making it the [[Abundance of the chemical elements|78th most abundant element]].{{sfnp|Greenwood|Earnshaw|1997|p=1071}} It is generally found in ores with the other platinum group metals in the [[Ural Mountains]] and in North and South America. Small but commercially important quantities are also found in [[pentlandite]] extracted from [[Greater Sudbury|Sudbury]], [[Ontario]], Canada, and in [[pyroxenite]] deposits in [[South Africa]]. The native form of ruthenium is a very rare mineral (Ir replaces part of Ru in its structure).<ref name="USGS-YB-2006">{{cite web |url = http://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2006-plati.pdf |publisher = United States Geological Survey USGS |access-date = 2008-09-16 |title = 2006 Minerals Yearbook: Platinum-Group Metals |first = Micheal W. |last = George |archive-date = 11 January 2019 |archive-url = https://web.archive.org/web/20190111062032/https://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2006-plati.pdf |url-status = dead }}</ref><ref name="USGS-CS-2008">{{cite web |url = http://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2008-plati.pdf |publisher = United States Geological Survey USGS |access-date = 2008-09-16 |title = Commodity Report: Platinum-Group Metals |archive-date = 11 January 2019 |archive-url = https://web.archive.org/web/20190111015125/https://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2008-plati.pdf |url-status = dead }}</ref> Ruthenium has a relatively high [[fission product yield]] in nuclear fission; and given that its most long-lived radioisotope has a half life of "only" around a year, there are often proposals to recover ruthenium in a new kind of [[nuclear reprocessing]] from [[spent fuel]]. An unusual ruthenium deposit can also be found at the [[natural nuclear fission reactor]] that was active in [[Oklo]], Gabon, some two billion years ago. Indeed, the isotope ratio of ruthenium found there was one of several ways used to confirm that a nuclear fission chain reaction had indeed occurred at that site in the geological past. Uranium is no longer mined at Oklo, and there have never been serious attempts to recover any of the platinum group metals present there.