Yttrium is a transition metal that was named after the the town of Ytterby, Sweden. Its chemical makeup is similar to a lanthanoid, and it is found in almost all rare earth minerals. Yttrium is used to make phosphors and LEDs, as well as having other uses in the electronics industry. YBCO, yttrium barium copper oxide, is a high-temperature superconductor. Yttrium-90 is a radioactive isotope used to treat cancer.