a greyish-white metallic element, occurring chiefly in zircon, that is exceptionally corrosion-resistant and has low neutron absorption. It is used as a coating in nuclear and chemical plants, as a deoxidizer in steel, and alloyed with niobium in superconductive magnets. Symbol: Zr; atomic no: 40; atomic wt: 91.224; valency: 2, 3, or 4; relative density: 6.506; melting pt: 1855±2°C; boiling pt: 4409°C