SM
Samarium (Sm) is a chemical element with the symbol Sm and atomic number 62. It is a soft, silvery metal in the lanthanide series and is considered a rare earth element. In nature, samarium occurs in several minerals, especially monazite and bastnasite, and is typically separated from other rare earths during ore processing by solvent extraction and ion-exchange methods. The most important isotope for dating is samarium-147, which decays to neodymium-143 with a half-life on the order of 106 billion years, providing a basis for Sm–Nd radiometric dating used in geology and planetary science. The most common oxidation state is +3.
Pure samarium is relatively reactive and oxidizes in air. It forms compounds such as the oxide Sm2O3
Samarium was identified in 1879 by Paul-Émile Lecoq de Boisbaudran in the mineral samarskite and named after