Raman and scanning electron microscopy and energy‐dispersive x‐ray techniques for the characterization of colouring and opaquening agents in Roman mosaic glass tesserae

Abstract

Abstract Mosaic tesserae, part of Roman villa floor decorations, from north‐eastern Sicily and the Aeolian Islands, were analysed by means of micro‐Raman spectroscopy and scanning electron microscopy–energy‐dispersive x‐ray techniques. Archaeologists considerate these ‘villa’ floor decorations (ranging from the 2nd century BC to the 4th century AD ) as a stylistic product of North African workers or North African‐style design that were imported from abroad. Much attention is paid in the technology of glass making in order to understand the capability of local workers to produce the same glassy material. Since the other coloured tesserae are definitively recognized as polished limestones and/or calcscists of well‐known Sicilian geological formations, the glassy materials could be hypothetically interpreted in the same way. Spectroscopic and mineralogical techniques were applied to the materials in order to define both the colouring and opaquening agents. Bindheimite (Pb 2 Sb 2 O 7 ), well known in past as ‘antique yellow’, was always found in both green and yellow glass tesserae, acting either as a colouring and/or an opacifier agent. Investigations were made in order to consider the possibility of local manufacturing techniques on the basis of widespread easy‐to‐find complex sulfide ore deposits in the area. Copyright © 2004 John Wiley & Sons, Ltd.