Uranium /(?)/

U·ra·ni·um

Uranium

n.
  1. An element of the chromium group, found in certain rare minerals, as pitchblende, uranite, etc., and reduced as a heavy, hard, nickel-white metal which is quite permanent. Its yellow oxide is used to impart to glass a delicate greenish-yellow tint which is accompanied by a strong fluorescence, and its black oxide is used as a pigment in porcelain painting. Symbol U. Atomic weight 239. <--radioactive, U-235 isotope is used in atomic fission, in bombs or power plants --> (Chem.)