Where does uranium occur in the natural envrionment?
Most rocks contain trace amounts of uranium (bulk concentrations on the order of 2 to 4 parts per million), however, uranium is not distributed uniformly through rocks, but tends to be concentrated in certain minerals. Some common accessory minerals in igneous, metamorphic, and sedimentary rocks, such as apatite and zircon, contain 2 to 1000 ppm uranium. Ore minerals like pitchblende, a variety of uraninite, uraninite (85 per cent uranium), carnotite, autunite, uranophane, and tobernite have uranium concentrations that are high enough to be economically mined. In addition, uranium can also be recovered in commercial quantities from coal and monazite sands. Uranium also occurs naturally in surface and ground water and in the ocean.
