HJELM, PETER JACOB

born 1746 died 1813 Swedish chemist who discovered the element molybdenum in 1782. Educated at the University of Uppsala, in 1782 Hjelm became master of assaying for the Royal Mint, Stockholm, and in 1794 was appointed director of chemical laboratories at the Swedish bureau of mines. His research interests included mineralogy, metallurgy, and industrial chemistry. He is credited with the observation that pig iron made from ore containing manganese, which he isolated successfully in 1781, frequently produced superior steel.