This work depicts a synthesis of the main water-rock interaction processes controlling the water chemistry in El Berrocal granitic pluton, emphasizing in the uranium geochemistry. An uranium-sulphide dyke controls the general characteristics of the system at the site scale. Dissolution/precipitation of calcite Is the m ost im p o rta n t process in the area. U ra n iu m concentration ranges from 4x10 ~9M to 8x10 ' 6M .
Undersaturation with respect to most of uranium minerals occurs in the water. Adsorption processes can be considered as main mechanism of uranium retention