Uranium constitutes about two parts per million of Earth’s crust. Some important uranium minerals are pitchblende (impure U3O8), uraninite (UO2), carnotite (a potassium uranium vanadate), autunite (a calcium uranium phosphate), and torbernite (a copper uranium phosphate). These and other recoverable uranium ores, as sources of nuclear fuels, contain many times more energy than all the known recoverable deposits of fossil fuels.
