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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 ...
The effect of odd-numbered chemical elements generally being more rare in the universe was empirically noticed in 1914, and is known as the Oddo–Harkins rule. The following graph ( log scale ) shows abundance of elements in the Solar System .
The rarest elements in the crust are not the heaviest, but are rather the siderophile elements (iron-loving) in the Goldschmidt classification of elements. These have been depleted by being relocated deeper into the Earth's core; their abundance in meteoroids is higher.
In the universe, thorium is among the rarest of the primordial elements at rank 77th in cosmic abundance [74] [79] because it is one of the two elements that can be produced only in the r-process (the other being uranium), and also because it has slowly been decaying away from the moment it formed.
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 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 ...
It is also the rarest primordial isotope in the Universe, taking into account the elemental abundance of tantalum and isotopic abundance of 180m Ta in the natural mixture of isotopes (and again excluding radiogenic and cosmogenic short-lived nuclides). [32]
With an estimated average concentration of 1 part per billion (ppb), rhenium is one of the rarest elements in the Earth's crust. It has one of the highest melting and boiling points of any element. It resembles manganese and technetium chemically and is mainly obtained as a by-product of the extraction and refinement of molybdenum and copper ores.