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A rare-earth mineral contains one or more rare-earth elements as major metal constituents. Rare-earth minerals are usually found in association with alkaline to peralkaline igneous magmas in pegmatites or with carbonatite intrusives. Perovskite mineral phases are common hosts to rare-earth elements within the alkaline complexes.
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 ...
Terbium is not distinguished from other rare earths in the United States Geological Survey's Mineral Commodity Summaries, which in 2024 estimated the global reserves of rare earth minerals at 110,000,000 tonnes (2.4 × 10 11 lb). [60]
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 ...
In this process, rare-earth ions are sorbed onto suitable ion-exchange resin by exchange with hydrogen, ammonium or cupric ions present in the resin. The rare earth ions are then selectively washed out by suitable complexing agent. [41] Erbium metal is obtained from its oxide or salts by heating with calcium at 1450 °C under argon atmosphere. [41]
The principal current source are some of the ion-adsorption clays of southern China. Some of these have a rare-earth composition similar to that found in xenotime or gadolinite. Yttrium makes up about two-thirds of the total by mass; holmium is around 1.5%. [47] Holmium is relatively inexpensive for a rare-earth metal with the price about 1000 ...
Rare-earth magnet, a type of magnet that employs rare earth elements to increase effectiveness; Rare Earth hypothesis, the theory that complex life in the universe is exceptionally rare; as a proper noun: Rare Earth: Why Complex Life Is Uncommon in the Universe, a book by Peter Ward and Donald E. Brownlee; Rare Earth (band), an American musical ...
Allanite contains up to 20% rare-earth elements and is a valuable source of them. The inclusion of thorium and other radioactive elements in allanite results in some interesting phenomena. Allanite often has a pleochroic halo of radiation damage in the minerals immediately adjacent.