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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 ...
See: Rare earth industry in China.) Although current evidence suggests rare-earth elements are less abundant on the Moon than on Earth, [60] NASA views the mining of rare-earth minerals as a viable lunar resource [61] because they exhibit a wide range of industrially important optical, electrical, magnetic and catalytic properties. [1]
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 study authors, however, suggest the value from extracting rare earth metals could be used to offset the costs of improving the way coal ash is stored and managed.
Most rare earth elements are located in China, with the world’s second-largest economy estimated to account for 70% of global rare earth ore extraction and 90% of rare earth ore processing.
On Earth, thorium and uranium are the only elements with no stable or nearly-stable isotopes that still occur naturally in large quantities as primordial elements. [a] Thorium is estimated to be over three times as abundant as uranium in the Earth's crust, and is chiefly refined from monazite sands as a by-product of extracting rare-earth elements.
It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". [8] Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element.
The overwhelming majority of rare-earth elements, tantalum, and lithium are found within pegmatite. Ore genesis theories for these ores are wide and varied, but most involve metamorphism and igneous activity. [10] Lithium is present as spodumene or lepidolite within pegmatite. Carbonatite intrusions are an important source of these elements ...