RELATIONSHIP BETWEEN THE COLORATION AND THE FIRING TECHNOLOGY USED TO PRODUCE SUSA GLAZED CERAMICS OF THE END OF THE NEOLITHIC PERIOD*

Ancient decorated potteries from Susa (Mesopotamia) dating from 4200 to 3700 bc , were studied in order to determine the origin and the nature of the raw materials used, and to identify the technological processes applied to make the ceramic bodies and their decorations. Bulk compositions were determined by particle induced X‐ray emission (PIXE), while the microstructure and the mineralogical phases were studied using scanning electron microscopy (SEM), energy dispersive X‐ray analyses (EDX) and X‐ray powder diffraction (XRD). The results showed that the raw materials used to elaborate these potteries were similar for all the ceramic bodies (carbonates and iron and magnesium‐rich clays containing sand), and for all the decorations (iron oxides, silica, potassic and alumina sources). The variations of coloration of the ceramics and of their decorations were due to different firing temperatures. The ranges of firing temperatures used by potters were evaluated on the basis of mineral stability domains.     

SPECTROSCOPIC INVESTIGATION OF RED STAINS AFFECTING THE CARRARA MARBLE FAÇADE OF THE CERTOSA OF PAVIA

The nature of the large red stains exhibited on the Carrara marble elements of the Certosa of Pavia façade was investigated by means of spectroscopic techniques and scanning electron microscopy. Although previous microbiological analysis has demonstrated the presence on the stone of a bacterial strain identified as Micrococcus roseus, that is capable of carotenoid production, it has been ascertained in the present study that an inorganic pigment, namely Pb₃O₄, is responsible for the observed coloration. On small green spots, the presence of photosynthetic micro-organisms has been demonstrated by microbiological analysis and confirmed by resonance Raman spectroscopy.