Scheele discovered Molybdenum in 1778. Molybdenum is a silvery-white metal that is ductile and highly resistant to corrosion. It has one of the highest melting points of all pure elements — only the elements tantalum and tungsten have higher melting points. Because of its very high melting point, it is produced and sold as a grey powder. Compressing the powder at a very high pressure forms many molybdenum items. Molybdenum is also softer and more ductile than tungsten. It was often confused with graphite and lead ore. Molybdenum is considered a micronutrient essential for life.
The main molybdenum ore is molybdenite but it can also be found in wulfenite and powellite. It is recovered as a by-product of copper or tungsten mining. Molybdenum is mined primarily in the United States, China, Chile and Peru.
As a transition metal, molybdenum easily forms compounds with other elements. Molybdenum is a valuable alloying agent, as it contributes to the hardenability and toughness of tempered steels. It also improves the strength of steel at high temperatures. The Second World War German artillery piece called “Big Bertha” contains molybdenum as an essential component of its steel.
It is used in certain nickel-based alloys, such as the Hastelloys(R) which are heat-resistant and corrosion-resistant to chemical solutions. Molybdenum oxidizes at elevated temperatures and when in contact with acid will slowly be corroded.
The metal has found recent application as electrodes for electrically heated glass furnaces and foreheaths. The metal is also used in nuclear energy applications and for missile and aircraft parts. Molybdenum is valuable as a catalyst in the refining of petroleum. It has found applications as a filament material in electronic and electrical applications. Molybdenum powders are used in circuit inks for circuit boards, and in microwaves devices and heat sinks for solid-state devices.
Molybdenum is an essential trace element in plant nutrition. Without Molybdenum in the soil, some lands become barren. Molybdenum sulfide is useful as a lubricant, especially at high temperatures where oils would decompose. As with other trace metals, though, what is essential in tiny amounts can be highly toxic at larger doses. Animal experiments have shown that too much molybdenum causes fetal deformities.