Bacterial leaching of uranium ores in the Elliot Lake area has been used as a production method since 1962. Minor amounts were recovered from mine waters prior to this. Uranium in a pyritized quartz pebble conglomerate is oxidized from the tetravalent to the hexavalent state in the presence of bacteria. The bacteria are naturally occurring autotrophs of the Ferrobacillus-Thiobacillus group. The solubilized uranium is then dissolved with water or acid solution and pumped to surface for treatment. Recovery of ammonium diuranate from the resulting acid mine water is carried out in a conventional uranium ion exchange plant. The method produces uranium at low cost from abandoned or caved mine workings. Recovery of thorium and rare earths by the same method is limited only by market conditions.