Molybdenum

Element, chemical symbol Mo. A grayish metal that does not easily tarnish in air and has a high melting point of 2620°C (4748°F). Its use as an alloying element in steel increases hardenability and in low alloy steels reduces the risk of temper brittleness. When added to stainless steels it increases their resistance to corrosion. It is also used in high-speed steels.