Figure 1: Back-scattered electron image by EPMA before leaching. ((a), (b), and (c)) Uranium minerals accompanied by pyrite. (b) Uranium minerals are located in the tiny fractures of quartz. (c) Uranium minerals are located in the tiny fractures of illite. ((a) and (b)) Images from Zhihua Wang and Baoqin Hu (2013) and (c) Xinbo Zhao (2014).