I vetri della Rocca di Monselice: studio archeometrico

The archaeometric study of glass from Rocca di Monselice (Italy) focuses on 8 samples characterised by the same archaeological type, the goblet Isings 111, and a well-defined date, with the aims of identifying raw materials and production technology used during the 7th century AD, analogies or differences with early Medieval glass from the Mediterranean area, and possible relationships between chemical composition and archaeological type. These aims were performed by combining chemical analyses carried out by means of X-ray fluorescence (XRF) and electron micro-probe (EMPA), and multivariate statistical treatment of chemical data. Results of chemical analyses show that all the samples are silica-soda-lime in composition, with natron as a flux, in accordance with the production technology of the period of interest. Multivariate statistical analysis allow us to split the Monselice samples into three compositional groups; two are chemically comparable to literature groups named Levantine 1 (4 samples from Monselice) and Group 2 (2 samples), respectively, and the third shows an intermediate composition between Levantine 1 and Group 2 (2 samples). The preponderance, in Monselice, of glass samples with Levantine 1 composition, as well as their good chemical comparability with those coming from the primary furnaces of the Syro-Palestinian coast, without evidence of recycling, supports the hypothesis of wide diffusion in Mediterranean area of this glass composition, which reaches its circulation peak during 7th-8th centuries AD. In Monselice assemblage, the occurrence of samples with other chemical compositions, but having the same archaeological type and date, demonstrates, as already pointed out in other Italian sites, that there is not direct correlation between archaeological type and chemical composition, at least for very common types, such as the goblet Isings 111.