1 IntroductionThe sandstone-hosted interlayer oxidation-zone typeuranium deposits are economically the most importanturanium resources in China (Zheng, 2001). Theseformations are thought to have a similar genesis to the well-known sandstone-hosted roll-type uranium deposits foundin Colorado, United States. It is believed that hexavalenturanium reduction in such deposits occurred soonafter sandstone sedimentation, when the permeability washigh enough to allow passage of ore-forming fluids (Na…