Samarium

Samarium is a silvery metal in the lanthanide family, a group of related rare-earth metals. It slowly reacts with air, so freshly prepared metal soon loses its shine. In nature, samarium is mixed with other rare-earth elements in minerals such as monazite and bastnäsite; it is not found as a free metal. After the minerals are processed, samarium is separated from its neighbors and can be recovered as a metal by electrolysis or by chemical reduction. Its most important use is in samarium–cobalt magnets, whose magnetic properties remain useful at temperatures that can weaken many other magnets. A different form, the radioactive isotope samarium-153, is used in a medicine that helps relieve pain from cancer that has spread to bone.