Peter Jacob Hjelm

1746-1813

Swedish chemist who first isolated the element molybdenum in 1782. Today, molybdenum is used to strengthen steel and other metals for use at high temperatures.

Hjelm also discovered that iron ore containing the element manganese produced steel that was harder and more resistant to corrosion than other steels. Hjelm was appointed master of assaying for the Royal Mint of Sweden. (Assaying is the process of determining the proportions of metals in ores or metal objects such as coins.)