The ceramics industry, given the high volume of materials processed, stands as one of the largest consumers of natural raw materials but has also the capacity and potential to make significant contributions to solving environmental problems associated with other industries rejects. This work investigates the effects of quartz sand replacement by agate rejects (scrap) in a traditional triaxial porcelain composition. The study was carried out using the design of experiments (DoE) method. Characterization results were used to calculate statistically significant and valid regression equations, relating dried and fired body properties with clay, feldspar and agate scrap contents in the unfired mixture. The regression models were then discussed against X-ray diffraction and scanning electron microscopy results and used simultaneously to delimit the combinations of those three raw materials most adequate to produce a porcelainized stoneware floor tile with specified properties. Thus, an alternative use of an otherwise waste material is proposed, which can be translated into economic benefits and an important and welcome relief on environmental and waste disposal concerns.