{{Short description|Radioactive variety of uraninite}} [[File:Clevite sample (35321726345).jpg|thumb|The cleveite sample from which Ramsay first purified helium, in the collection of University College London<ref name="Kirk">{{cite web|last1=Kirk|first1=Wendy L.|title=Cleveite [not Clevite] and helium|url=https://blogs.ucl.ac.uk/museums/2013/01/11/cleveite-and-helium-not-clevite/|website=Museums & Collections Blog|publisher=University College London|accessdate=18 August 2017}}</ref>]] '''Cleveite''' is an impure radioactive variety of uraninite containing uranium, found in Norway. It has the composition UO<sub>2</sub> with about 10% of the uranium substituted by rare-earth elements.<ref>http://www.mindat.org/min-29957.html Mindat.</ref> It was named after Swedish chemist Per Teodor Cleve.
Cleveite was the first known terrestrial source of helium, which is created over time by alpha decay of the uranium and accumulates trapped (occluded) within the mineral. The first sample of helium was obtained by William Ramsay in 1895 when he treated a sample of the mineral with acid.<ref>https://archive.org/details/becquerelraysthe00raylrich Rayleigh, Robert and John Strutt, 1904, The Becquerel rays and the properties of radium, London, E. Arnold.</ref> Cleve and Abraham Langlet succeeded in isolating helium from cleveite at about the same time.
Yttrogummite is a variant of cleveite also found in Norway.
==See also== {{Portal|Earth sciences}} * List of minerals * List of minerals named after people
==References== <references/>
Category:Uranium(IV) minerals Category:Thorium minerals Category:Oxide minerals
{{oxide-mineral-stub}}