| The element is never found in nature in pure form, but it is found in small quantities in minerals with other rare earths. It is principally extracted from monazite (~0.007% thulium) ores found in river sands through ion-exchange. Newer ion-exchange
and solvent extraction techniques have led to easier separation of the rare earths, which has yielded much lower costs for thulium production. The principal source today are the ion adsorption clays of southern
China. In the versions of these, where about two-thirds of the total rare earth content is yttrium, thulium is about 0.5% (or about tied with lutetium for rarity). The metal can be isolated through reduction of its oxide with lanthanum metal or by calcium reduction in a closed container. None of thulium's compounds are commercially important.
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Occurrence