Physicochemical investigation of medieval ceramics from excavation site Novo Brdo

Artefacts produced or treated at high temperatures provide information about manufacturing techniques. Well preserved ceramic objects are therefore excellent chronological markers as well as general markers of society development. In order to determine provenance of pottery fragments, archaeologists classify samples according to their physical characteristics, decoration and aesthetic style. However, a more objective multidisciplinary approach, based on undoubted results, is necessary to complete this study. In this work we have investigated 27 samples of medieval ceramics from excavation site Novo Brdo, using X-ray fluorescence (XRF), FTIR spectroscopy and X-ray powder diffraction (XRPD). Novo Brdo was large and rich mining and trading center of Serbia in XIV and XV century. A large number of ceramic samples found during the systematic excavation of this archaeological site allow good choice of samples for both destructive and nondestructive analysis. Combining results obtained by different experimental techniques, i.e. by FT-IR spectroscopy, after deconvolution of the spectra, and XRPD analysis, we have determined mineralogical composition and technology of production of investigated pottery. Estimated temperature of firing ranged from 800 to 900 °C, which is in agreement with the presence of high-temperature minerals like gehlenite and anorthite. Firing was preformed in the oxidation atmosphere since hematite, which is formed only in oxidation atmosphere, is detected in all investigated samples. Cross sections showed presence of defects and inhomogeneity of investigated ceramic, which indicates fast and incomplete firing procedure. All these findings indicate that investigated pottery was produced in the domestic workshops. The obtained results will be used to build up the National database for medieval ceramics as well as the database for the Balkan region.