Molybdenum is named from the Greek molybdos, lead and was first recognized as a distinct element in 1778. Molybdenum does not occur native, but is obtained primarily from molybdenite. Wulfenite and powellite are also minor commercial ores. Molybdenum is also recovered as a by-product of copper and tungsten mining operations. The metal is silvery-white, very hard, but softer and more ductile than tungsten. Molybdenum is a valuable alloying agent, is used as electrodes for electrically heated furnaces and is used for missile and aircraft parts. Molybdenum sulfide is used as a lubricant, especially at high temperatures where oils would decompose.