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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 ...
Iridium is one of the rarest elements in Earth's crust, with an estimated annual production of only 6,800 kilograms (15,000 lb) in 2023. The dominant uses of iridium are the metal itself and its alloys, as in high-performance spark plugs , crucibles for recrystallization of semiconductors at high temperatures, and electrodes for the production ...
The Earth's crust is one "reservoir" for measurements of abundance. A reservoir is any large body to be studied as unit, like the ocean, atmosphere, mantle or crust. Different reservoirs may have different relative amounts of each element due to different chemical or mechanical processes involved in the creation of the reservoir.
Rare-earth ore, shown with a United States penny for size comparison. 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 complexes in pegmatites. This would be associated with alkaline magmas or with carbonatite ...
Manufacturers use its alloys with platinum, iridium, and other platinum-group metals to make fountain pen nib tipping, electrical contacts, and in other applications that require extreme durability and hardness. [12] Osmium is among the rarest elements in the Earth's crust, making up only 50 parts per trillion . [13] [14]
Astatine is the rarest naturally occurring element. [j] The total amount of astatine in the Earth's crust (quoted mass 2.36 × 10 25 grams) [108] is estimated by some to be less than one gram at any given time. [8] Other sources estimate the amount of ephemeral astatine, present on earth at any given moment, to be up to one ounce [109] (about ...
Furthermore, the rare earth metals are all quite chemically similar to each other, and they are thus quite difficult to separate into quantities of the pure elements. Differences in abundances of individual rare earth elements in the upper continental crust of the Earth represent the superposition of two effects, one nuclear and one geochemical.
Although aluminium is the third most abundant element and the most abundant metal in the Earth's crust, it was at first found to be exceedingly difficult to extract the metal from its various non-metallic ores. The great expense of refining the metal made the small available quantity of pure aluminium more valuable than gold. [16]