Praseodymium is named from the Greek prasios, gren, and didymos, twin and was discovered in 1885. The element occurs along with other rare-earth elements in a variety of minerals. Monazite and bastnasite are the principal commercial sources of the rare-earth metals. The metal is isolated using ion exchange and solvent extraction methods. Praseodymium is a soft, silvery-white, malleable and ductile metal. Praseodymium is a component of misch metal, and along with other rare-earth metals is widely used as a core material for carbon arc lamps used by the motion picture industry.