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The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), [1] are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. Compounds containing rare ...
Like other rare earths, this element is never found as a free element in nature but is found in monazite and bastnäsite ores. [9] It has historically been very difficult and expensive to separate rare earths from each other in their ores but ion-exchange chromatography methods [ 43 ] developed in the late 20th century have greatly reduced the ...
Like most other rare earth elements, its usual oxidation state is +3, although some compounds are known with an oxidation state of +2. Lanthanum has no biological role in humans but is used by some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity. Lanthanum usually occurs together with cerium and the ...
Thus an indication of these minerals being short in supply and allocated their title as 'rare' earth minerals. [4] Many rare-earth minerals include rare-earth elements which thus hold the same significant purpose of rare-earth minerals. [5] Earth's rare minerals have a wide range of purposes, including defense technologies and day-to-day uses. [6]
Has no known biological role, and is extremely rare in the Earth's crust. The isotope plutonium-238 is used as an energy source in some heart pacemakers. [11] Both toxic and radioactive. polonium: 84: 1b: Has no known biological role, and due to its short half-life, is nearly nonexistent outside of research facilities. [11] Both highly toxic ...
The study shows that more than 16 million short tons (15 billion kilograms) of rare-earth elements could be "exploited in the near future." As well as yttrium (Y), which is used in products like camera lenses and mobile phone screens, the rare-earth elements found are europium (Eu), terbium (Tb), and dysprosium (Dy). [55]
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Xenotime is a rare-earth phosphate mineral, the major component of which is yttrium orthophosphate (Y P O 4).It forms a solid solution series with chernovite-(Y) (Y As O 4) and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium.