Environmental protection drives the search for materials which can be used in preventing soil and water degradation and in pollutant removal. Chalcedony belongs to this category. It is a unique mineral, occurring in several areas in the Central Poland. Excavated material has been used for many years as aggregate in road construction although it is not suitable for this purpose due to its properties. Studies have shown its properties can best be used in drinking water treatment, especially in eutrophic reservoirs. Thus, chalcedony deposits should be protected as the source of filtration materials.