Only about three kilograms of uranium oxide are recovered from each tonne of ore. The left-overs, looking like liquid mud and called tailings, are pumped into a tailings dam.
The radium below the surface can only be exposed by erosion. This erosion is usually the result of the action of carbonic acid in the ground water
Radon is continually being formed in soil and released to air as a result of the extended half-lives of uranium and radium and their abundance in the earths surface.