Uranium

Uranium is a radioactive, silvery-gray metal in the actinide family. It occurs naturally in small amounts in rocks, soil, and water, but useful supplies come from uranium-bearing minerals such as uraninite. Miners extract uranium ore and process it to concentrate the uranium. Most natural uranium is uranium-238, while less than one percent is uranium-235. In many nuclear power plants, uranium fuel is enriched to increase the share of uranium-235, whose atoms can split and release energy in a sustained chain reaction. Uranium-238 can also be converted in a reactor into plutonium-239, another fuel. Uranium compounds have also colored glass and ceramics; this is a use of compounds, not the metal itself.