Archaeometric Provenance Constraints for Early Medieval Sparse Glazed Pottery from Donoratico (Livorno, Italy)

The study of a huge repertory of sparse glazed ware from Donoratico (Livorno, Italy) dated back to the ninth century was carried out to investigate the production technology via petrographic, chemical, and isotopic investigations. The mineralogical and chemical evidence suggested the application of a lead oxide flux to an unfired non-calcareous ceramic body, in accordance with late Antique and early-Medieval traditions. The isotopic investigation of the glazes also suggested different sources for PbO, which was frequently applied as a mix of different metal batches. The Pb isotopic record identified the Southern Tuscany districts (Campiglia Marittima and Colline Metallifere) and a source controlled by the Carolingian kings in the northern districts of Central Europe (either in Aquitaine or in the Middle German ore districts) as the most reliable sources. SEM-EDS showed the presence of tin impurities in the form of secondary cassiterite agglomerates in most of the glazes obtained by the use of local lead. The presence of cassiterite veins in Southern Tuscany lead sulphide deposits was considered as the main cause for tin impurities in the glazing mixture and, thus, an important marker for the exploitation of local lead.