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Mineral Components Mainly Comprise Rare Earths Metals

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Ben Wood
Mineral Components Mainly Comprise Rare Earths Metals

Chemical changes are brought on by the light and heavy rare-earth elements' atomic numbers increasing and their atomic radii decreasing over the course of the series. This classification does not apply to europium because it has two valence states, Eu2+ and Eu3+. Yttrium belongs to the heavy Rare Earths Metals element group because of its chemical resemblances. Sometimes the division between the two groups is placed between elements 63 (europium) and 64. (gadolinium).

The "light" group has densities ranging from 6.145 (lanthanum) to 7.26 (promethium) or 7.52 (samarium) g/cc, while the "heavy" group has densities ranging from 6.965 (ytterbium) to 9.32 (thulium), as well as yttrium at 4.47. The actual metallic densities of these two groups overlap. The density of europium is 5.24.


These metals react slowly with cold water to form hydroxides, which release hydrogen, and tarnish gradually in air at room temperature. They create oxides when they interact with steam, which ignite spontaneously at a temperature of 400°C. Apart from a few specialised enzymes, like lanthanide-dependent methanol dehydrogenases in bacteria, these elements and their compounds serve no biological purpose. The insoluble compounds are not toxic, whereas the water-soluble ones are mildly to moderately toxic. Contrary to what they are called, rare-earth elements are actually quite common in the crust of the Earth, with cerium being the 25th most common element with 68 parts per million, more common than copper. Except for a tiny amount produced by spontaneous fission of uranium-238, all promethium isotopes are radioactive and do not naturally exist in the earth's crust. They are frequently discovered in thorium- and less frequently uranium-containing minerals.



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