Abstract:Sandstone-type uranium ore is mainly mined by in-situ leaching. During in-situ leaching process, leaching agent does not only react with uranium-bearing minerals, but also react with a large number of gangue minerals in ore. Under different leaching conditions, geochemical behavior of minerals in formations is also different. According to composition of leaching agent, leaching techniques can be divided into four kinds: acid leaching, alkali leaching, neutral leaching and microbial leaching. The geochemical characteristics of different minerals in ore bearing layers under specific leaching process conditions and their possible influence on leaching process were reviewed. Feldspar, mica, and carbonate, under acidic conditions, consume acids and oxidizing agents, and altering themselves to form clays, then maybe they precipitate, and reacted gases can cause blockages. Sulfides, such as pyrite, consume oxidants and may precipitate iron under alkaline leaching conditions. Clay minerals may swell to reduce permeability of ore beds. Neutral leaching and microbial leaching are new in-situ leaching, but there are also some problems, which need to be solved in the follow-up research.