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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 ...
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 ...
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]
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 ...
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]
Neodymium is a fairly common element in the Earth's crust for being a rare-earth metal. Most rare-earth metals are less abundant. Neodymium is classified as a lithophile under the Goldschmidt classification, meaning that it is generally found combined with oxygen. Although it belongs to the rare-earth metals, neodymium is not rare at all.
Only 0.2% of the rare-earth element content is europium. The second large source for rare-earth elements between 1965 and its closure in the late 1990s was the Mountain Pass rare earth mine in California. The bastnäsite mined there is especially rich in the light rare-earth elements (La-Gd, Sc, and Y) and contains only 0.1% of europium.
Praseodymium is not particularly rare, despite it being in the rare-earth metals, making up 9.2 mg/kg of the Earth's crust. [43] Praseodymium's classification as a rare-earth metal comes from its rarity relative to "common earths" such as lime and magnesia, the few known minerals containing it for which extraction is commercially viable, as ...