This study aims to determine the presence of fluid inclusions, and investigate their types, structures, and compositions in natural pure chalcopyrite. The study also aims to measure the total concentrations of Cu (C-CuT) and Fe (C-FeT) released from the inclusions. Results indicate that large numbers of fluid inclusions with sizes ranging from a few to dozens of microns exist in the chalcopyrite, and that these fluid inclusions are isolated and concentrated. The fluid inclusions take on various shapes-long strip, oval shape, and irregular and exhibit a directional distribution along the chalcopyrite crystal growth zone. The inclusion body sizes fall between 3 and 60 mu m, with lengths ranging from 3 mu m to 50 mu m and widths from 2 mu m to 30 mu m. The inclusions are rich in Cl-, SO42-, Cu, Fe, and so on because they capture diagenesis fluid and mineralizing fluid during the ore-forming process. The compositions of inclusions are broken when released to solution through the grinding process. In the experimental conditions of 2 g chalcopyrite placed into 40 ml pure deionized water under an inert environment, C-CuT and C-FeT released from the inclusions reach concentrations of 5.79 x 10(-6) and 17.20 x 10(-6) mol/L, respectively. These values are much higher than those from the experimental dissolution under an inert environment (0.05 x 10(-6) and 0.12 x 10(-6) mol/L, respectively). Therefore, the release of Cu and Fe from the inclusions is the new source of Cu and Fe concentration in the solution. This finding sheds new light on the source of unavoidable ions in the flotation pulp. The residual position domain after the release of the inclusions causes the morphology difference in the chalcopyrite surface composition and roughness. Discovering that fluid inclusions are the new source of unavoidable ions in the flotation pulp is significant in the study of flotation theory and environmental geochemistry. (c) 2012 Elsevier Ltd. All rights reserved.