Archaeometric Analyses of Iron Age glass beads from Veneto Area (Italy)

The research is focused on the chemical and mineralogical study of protohistoric glass beads coming from Northern Italy (Piovego necropolis in Padova and Villa di Villa sanctuary near Treviso) dated to the Iron Age. The composition and texture of glassy materials are investigated in order to shed light on the evolution of production techniques. The samples were investigated with Scanning Electron Microscopy (SEM) combined with EDS and Electron Probe Microanalysis (EPMA). Backscattered electron images (BSE) were acquired to evaluate the texture and the morphology of the samples, while EDS analyses were obtained in order to characterise the nature of inclusions in the glassy matrix. Moreover, computerized 2-D image analysis was applied to BSE images to quantify the relative proportion between the glassy matrix and the unreacted grains. Most of the samples have an heterogeneous texture with metallic inclusions and mineral phases due to unreacted raw materials, newly formed crystals or opacifiers. Only one samples is a faience, while some others opaque beads are glassy faience (containing equal quantity of unreacted grains with respect to the glassy matrix). The EPMA data show that the samples are natron based, but chemical compositions have a large variability depending on the colour and opacity/transparency of the glass. The specific chemical composition and opacifiers/colorants identified will be presented and discuss comparing the age and the typology of the finds.