The Cu skarn-type mineralization in the Rio Frio mine seems to be related to Jurassic-Cretaceous rocks (Stock of Payande) that intrude Triassic limestones belonging to Payande Formation. Ore-body mapping, shows several zones, whose boundaries are gradual and the garnet color is controlled by the distance up to intrusive contact: the first zone corresponds to a fresh tonalite-cuarzodiorite, the second one corresponds to the endoskarn, the third one corresponds to the exoskarn: a prograde stage, characterized by garnet and pyroxene in lesser extent, and a retrograde stage, with the mineralization (iron oxides, iron and copper sulfides), actinolite-tremolite, euhedral quartz and calcite. Finally the marble zone with wollastonite and garnet. The most important textural relationships, between ore minerals are the martitization textures, exsolution textures, pseudo-eutectic textures and selective replacement textures. Fluid inclusions data from prograde garnet indicate a fluid with salinities of 25.76-26.12% NaCl and homogenization temperatures (Th) >580°C. Primary fluid inclusions in quartz, from the retrograde stage, indicate a fluid with salinities between 14.15-16.52% NaCl and homogenization temperatures between 270°-320°C. This is consistent with the presence of cubanite exsolved in chalcopyrite (geothermometer), indicating, according to Ramdorh (1980), temperatures between 250°-300°C. The minimal theoretical pressure is 211-230 bars, which correspond to minimal depths 800-1100m and minimal temperatures of formation of 300°-330°C for the retrograde skarn