The present work investigated the trace and component release of fluid inclusions in natural pure galena. The investigation results indicated that the composition of the inclusion trace was characterized by a lower Pb content compared to the theoretical composition of galena; nonetheless, these inclusions were rich in lead and chlorine ion. The inclusions were liberated through a grinding process where their compositions were released into solution. It was found that the lead concentrations (C-pbT) released from the inclusions through the grinding process reached 8.25 x 10(-6) mol/L in the experiment with conditions of 2 g galena placed into 40 ml pure deionized water under an inert environment, which was much higher than the CpbT found through experimental dissolution (1.12 x 10(-6) mol/L). Therefore, it was concluded that the release of Pb from the fluid inclusions in galena was an important new source of the Pb 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 galena surface composition and roughness. This study provided a new understanding of the unavoidable ion source that is found in the flotation theory and environmental geochemistry. (C) 2013 Elsevier Ltd. All rights reserved.