Lanthanum is named from the Greek lanthanein, to lie hidden and was discovered in 1839. Lanthanum is found in rare earth minerals such as cerite, monazite, allanite and bastnasite. Monazite and bastnasite are principal ores in which lanthanum occurs in percentages up to 25% and 38%, respectively. The metal is isolated using ion exchange and solvent extraction methods. Lanthanum is a silvery-white malleable, ductile and soft metal. Rare earth compounds containing lanthanum are used extensively in carbon lighting applications, especially in the motion picture industry.