The statues that adorn the Baptism and Birth porticos of the Cathedral of Seville (Spain) made by Lorenzo Mercadante de Bretaña have been studied. The results show that in the manufacture of this ceramic two different firing temperatures, below 950°C and over 950°C, were used. The possible material employed in their manufacture was lime marl consisting of illite, smectite, kaolinite, quartz, feldspars, calcite, and iron oxide. It has also been found that calcite nodules do not produce cracks in the ceramic.