AbstractPotential use of waste stone mud from the stone-processing industry has been studied. Waste stone mud can be used as a filler (opening agent), a flux or a glazing material, depending on the composition. It is mostly used in clay-based production, e.g. in the production of clay bricks, blocks, panels, roofing tiles, facing bricks, and ceramic pipes. Due to the partial replacement of basic raw materials by waste mud, quite a significant decrease in costs could be achieved and even the quality of final products improved in the case of high-plasticity basic clay. Mud containing 70 m.% on average of finely-grained silica sand is the residue after the screening of higher fractions of silica sand. Clays and feldspars are also present in certain amounts. Mixtures of clay and mud were prepared in different proportions (up to 50 m.% of mud). Besides water absorption, bulk density, and bending and compressive strengths of fired samples, the influence of the stone mud addition on drying and firing shrinkage was determined.