Abstract

Mosaic glass tesserae can be investigated from different angles, shedding light on a broad range of economical, technological and historical research issues. Appeared for the first time in the eastern Mediterranean, during the Hellenism, the earliest glass tesserae are precious and used sparingly. Later, during the Roman Empire, they become popular, thanks to the advancements of the glass technology. During the Byzantine period, they become the material of election for the large wall mosaics used to decorate the churches. Here, coloured glass tesserae are combined to a large amount of gold and, occasionally, silver glass tesserae. Although the economic value of glass tesserae surely changed through the centuries, it is certain that they have always been regarded as valuable materials, not only for making mosaics, but also for being recycled and reused. At least since the Late Antiquity, Roman tesserae are recycled for colouring glass cullet. During the Migration period they are re-melted, for making glass beads and, occasionally, deposited, as grave goods.

After introducing the basic principles of ancient glass technology and presenting the history of glass tesserae in the Mediterranean mosaic tradition, we will explore the potential of the interdisciplinary exploration of loose mosaic tesserae.  In order to investigate the main technological and economic issues, linked to the consumption and circulation of this fascinating material, we will discuss the preliminary results obtained by the chemical characterisation (by LA-ICP-MS, at CNRS-IRAMAT CEB, Orléans) of the glass tesserae excavated at Gerasa, Jordan, by the UrbNet archaeological mission.

The lecture is followed by an informal reception. All are welcome.