Research was carried out on the slopes of a tailings pond built from carbonate wastes, rich in metal flotation wastes of Mississipi Valley-Type Zn-Pb ores in the Silesia-Kraków ore district (southern Poland). These wastes, resulting from Zn-Pb ore processing, may have a detrimental impact on the environment. This study presents results of chemical (ICP, IC, AAS) and mineralogical (XRD, SEM-EDS) characterizations of material from the superficial waste layer, water runoff and relocated suspension. They indicate the occurrence of several secondary mineral phases (Fe oxide, Zn and Pb carbonate, and sulfate-containing metals), resulting from the weathering processes of primary Fe, Zn, and Pb sulfides. Results of XRD and SEM examinations point to the increase of sulfate mineral content in the top layer of wastes compared to the wastes in depth. Rainwater runoff (RWR) on the slopes of tailings is characterised by the prevalence of calcium and sulfate, as well as the presence of metals such as Zn, Fe, Mn, Sr and Cd. Metals and sulfates migration in RWR is one of the ways of contaminants’ spreading around Zn-Pb processing mine tailings.