Manufacture of prepared pigments, prepared opacifiers and prepared colours, vitrifiable enamels and glazes engobes and similar preparations of a kind used in the ceramic, enamelling or glass industry
Operation of sand or gravel pits, basalt / porphyry, clay (ordinary), crushing and breaking of stone for use as a flux or raw material in lime or cement, manufacture or as building material, road metal or ballast and other materials for construction