Archaeometric analysis of vitreous material ornaments from the Villa di Villa site (Treviso, Italy)

The research focused on chemical and mineralogical analyses of eight vitreous material ornaments with a not well-defined chronology, coming from the protohistoric and Roman site of Villa di Villa in Cordignano–Colle Castelir (Treviso, north-eastern Italy). Eleven microsamples from the bodies and decorations of the ornaments underwent wavelength-dispersive electron probe microanalysis, scanning electron microscopy combined with energy dispersive spectrometry (EDS) and micro-Raman Spectroscopy. Non-invasive X-ray powder diffraction was performed on the surface of the ornaments. All vitreous materials were obtained using natron as flux except for one annular blue bead produced with mixed alkali plant ashes. The analyzed dark blue glasses are Co colored, only the pale blue melon bead faïence is Cu colored. Opaque white and yellow glasses of two objects are opacified by Ca and Pb antimonates, respectively. The heterogeneous texture of some glasses is due to unreacted raw materials and/or newly formed crystals. The relationship between the Villa di Villa ornaments and coeval European/Mediterranean vitreous materials is also discussed. Composition, texture and morphological characteristics of the ornaments shed light on the different types of raw materials used and allow us to verify the main types of glass that occur during the great time span of life of the site and above all to answer to specific archaeological questions about possible chemical correlations between similar objects from the same or different SU. In two cases, the analytical data provide more detailed information about the ages of the ornaments.