A heavy, hard, lustrous, silver-white
metallic element, symbol Mo, atomic number
42, atomic weight 95.94. The chief ore is the
mineral molybdenite. The element is highly
resistant to heat and conducts electricity
easily. It is used in alloys, especially to
harden steels. It is a necessary trace
element in human nutrition. It was named in
1781 by Swedish chemist K W Scheele, after
its isolation by P J Helm (1746-1813), for
its resemblance to lead ore (from Greek
malybdos, lead). It has a melting point of
2,620 degrees C, and is not found in the free
state. As an aid to lubrication, molybdenum
disulphide (MoS2) greatly reduces surface
friction between ferrous metals. Producing
countries include Canada, the USA, and
Norway.