Colourless Roman glass from the Zadar necropolis: An exploratory approach

This paper presents the study of eighteen samples of colourless glass dated to the Roman period (1st to 3rd centuries C.E.) and that were unearthed in Zadar, Croatia. In this exploratory research, the chemical composition of the glass, which was determined by mu-PIXE, was divided into two main groups based on the alkali and alkali-earth contents: glass with low CaO and Al2O3, and high Na2O contents (Group 1), and glass with high CaO, Al2O3, and low Na2O contents (Group 2). The chemical composition from Group 1 is related to polygonal bottles and the composition from Group 2 to bell-shaped bottles, the latter being considered of local provenance. The analysis of MnO, Sb2O5 and Al2O3 contents and ratios suggests that only three samples from Group 1 were obtained from a primary glass source discoloured with Sb and the remaining fragments are the result of recycling activities, whereas all fragments from Group 2 were made using a different primary glass source discoloured with Mn. Finally, considering all the compositional characteristics of the analysed glass, it is proposed that the primary glass source of Group 1 was Egypt, and that glass from Group 2 came from the Levant region.