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The exception is the highly unstable and radioactive promethium "rare earth" is quite scarce. The longest-lived isotope of promethium has a half-life of 17.7 years, so the element exists in nature in only negligible amounts (approximately 572 g in the entire Earth's crust). [33]
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]
A rare species is a group of organisms that are very uncommon, scarce, or infrequently encountered. This designation may be applied to either a plant or animal taxon, and is distinct from the term endangered or threatened. Designation of a rare species may be made by an official body, such as a national government, state, or province.
For advanced industrial economies the commonly used terms "critical minerals" or "critical raw materials" refer to materials required for their strategic industries where there is a risk of interruption to supply. [5]
Rare radioactive natural elements; often produced artificially Common radioactive natural elements A synthetic element is one of 24 known chemical elements that do not occur naturally on Earth : they have been created by human manipulation of fundamental particles in a nuclear reactor , a particle accelerator , or the explosion of an atomic ...
Four decades ago, a rare earth processing plant on France's Atlantic coast was one of the largest in the world, churning out materials used to make colour televisions, arc lights and camera lenses.
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction. [ 24 ] [ 25 ] It is an interdisciplinary subject drawing on science, economics and the practice of natural resource management .
Quartzolite – Extremely rare igneous rock made mostly of quartz – An intrusive rock composed mostly of quartz; Rhyodacite – Volcanic rock rich in silica and low in alkali metal oxides – A felsic volcanic rock which is intermediate between a rhyolite and a dacite; Rhyolite – Igneous, volcanic rock, of felsic (silica-rich) composition