Short answers, pulled from the story.
French chemist Paul-Emile Lecoq de Boisbaudran identified samarium in Paris in 1879 by observing sharp optical absorption lines in the mineral samarskite. Pure samarium metal was not isolated until 1903, by Wilhelm Muthmann.
Samarium is named after the mineral samarskite, which honored Vassili Samarsky-Bykhovets (1803-1870), a Chief of Staff of the Russian Corps of Mining Engineers. He became the first person in history to have a chemical element named after him, though the honor came indirectly through the mineral.
The isotope samarium-153 is the active component of the drug Quadramet, used to kill cancer cells in lung cancer, prostate cancer, breast cancer, and osteosarcoma. It is chelated with ethylene diamine tetramethylene phosphonate and injected intravenously; samarium-153 has a half-life of 46.285 hours.
Samarium-149 is a powerful neutron absorber with a thermal neutron cross section of 41,000 barns, making it the second most important neutron poison for reactor design and operation after xenon-135. Unlike xenon-135, it is not radioactive and is only removed by neutron capture, so its concentration builds to an equilibrium level over roughly 500 hours of reactor operation.
Samarium-cobalt magnets have a permanent magnetization about 10,000 times that of iron and rank second only to neodymium magnets in magnetic strength. Their key advantage is heat resistance: they remain stable above 700 degrees Celsius, compared to 300-400 degrees Celsius for neodymium magnets.
China produces all of the world's usable samarium, with refining concentrated in Baotou. The sole Western production plant, in La Rochelle, France, closed in 1994, and a US government effort costing roughly one billion dollars to reopen Mountain Pass, California ended in bankruptcy. During the Trump administration's second-term tariff disputes, China imposed strict export limits on samarium, highlighting the supply chain vulnerability.