Promethium
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Promethium is a generally synthetic chemical element; it has symbol Pm and atomic number 61. All of its isotopes are radioactive; it is extremely rare, with only about 500–600 grams naturally occurrin
Promethium 147 solution
Promethium nitrate
Uraninite, a uranium ore and the host for most of Earth's promethium
Rare-earth element
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The rare-earth elements, also called rare-earth metals, or rare earths, are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. The 15 lanthanides, along with scandium, and
Promethium
…of 63 kg/mm2. This low-temperature alpha form converts into a beta, body-centered cubic (bcc) phase upon heating to 890 °C. Promethium belongs to the cerium group of lanthanides and is chemically very similar to the neighboring elements. Because of its instability, chemical studies of promethium are incomplete…
Rare-earth ore (shown with a 19 mm diameter US 1 cent coin for size comparison)
Refined rare-earth oxides are heavy, gritty powders usually brown or black, but can be lighter colors as shown here. Back row: gadolinium · praseodymium · cerium Middle row: samarium · lanthanum Front: neodymium