Glass and gold: Analyses of 4th-12th centuries Levantine mosaic tesserae. A contribution to technological and chronological knowledge

Fifty-eight gold leaf tesserae from eight archaeological sites situated in the Byzantine Empire and two Early Islamic (one in medieval Palestine), covering the period that goes from the 4th c. to the 12th c., were analysed by EPMA, SEM-EDS and PIXE-PIGE to determine the composition of both the glass and the gold leaves. The good match until the 6th c. between circulating monetary alloys and the gold leaf compositions together with the type of glass used, provided criteria that can be used to date the tesserae fabrication. The data obtained allow newly produced tesserae to be distinguished from re-used ones. Because after the 7th c. the circulation of gold in the Byzantine Empire was less controlled, the same relationship is harder to establish. The results suggest the existence of workshops in the Eastern and Western part of the Mediterranean and a more advanced technology to manufacture a palette of glass colours for gold leaf tesserae in the Eastern region. (c) 2016 Elsevier Ltd. All rights reserved.