Mercury (Hg) has been extensively used in Mexico since the 16th century for Au and Ag extraction by means of amalgamation. The excessive use of Hg over several centuries, however, resulted in significant Hg contamination in soils and mine waste, which can represent a significant health threat to local population. Following the Minamata Convention, this project aims at investigating various Hg contaminated sites in Cedral S.L.P., Mexico, including a mine tailing, an amalgamation plant and an ore reprocessing plant. We investigate the Hg content and distribution at the different sites in order to characterize the extent of contamination. Moreover Hg toxicity is highly dependent on its speciation and the Hg speciation at the different sites is also investigated. Additionally other metals (Cu, Zn, Pb, Ag, Sb…) are also investigated for other potential toxicity or eventual economic value. This project is financed by the Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit of Germany.