The response of Cu-oxide and sulfide ores is studied by the leaching of sulfuric acid. Exotic and supergenic enrichment samples were contrasted by assaying three Chilean copper deposits in order to develop a predictive methodology of the industrial process. The mineralogical and chemical characteristics of the ores were described, including clay-size fraction X-ray diffraction, cation exchange capacity and hydraulic conductivity. Leaching experiments included the re-extraction of Cu remaining in the heap and were performed in stages of rinsing and elution in order to quantify the Cu physically or chemically retained in the residues. The integral characterization and the assays permit to predict the leaching behavior of the studied units and make possible the necessary blend of them in the industrial process. A relevant conclusion was to confirm that the removal of clay minerals from the rock framework during leaching is dependent of the rock texture which resulted as the limiting variable for the final copper liberation or retention. (C) 2009 Elsevier Ltd. All rights reserved.