Fragile connections, persistent methodology. A tailor-made archaeometric protocol to investigate technological and cultural issues in the supply of glass tesserae under the Umayyad caliphate

In the panorama of ancient glass manufacture, several aspects concerning glass industry under the Umayyad caliphate still need to be investigated. While our knowledge of Umayyad glassware has been enhanced by recent research, when considering mosaic glass tesserae even a preliminary scenario is lacking. A pivotal issue addressed in this research concerns the relationship between Umayyad and Byzantine mosaic manufacture and technology. Several Muslim literary sources claim that Umayyad caliphs got from the Byzantine emperor workmen and materials to construct and decorate religious buildings, like the Prophet’s Mosque at Medina, the Dome of the Rock and the Great Mosque of Damascus. Nevertheless, the issue of the sent tesserae has arisen several problems, primarily due to the reliability of the sources. In addition, legacies other than Byzantine stem from other documents like the 8th CE Aphrodito papyri (reporting an official correspondence between the Governor of Egypt and the Prefect of the District of Aphrodito), referring to materials and craftsmen sent from Egypt to Jerusalem and Damascus, to collaborate on the construction of Umayyad mosques. The research focuses upon an archaeometric characterisation of three assemblages of Umayyad glass tesserae from Khirbat al-Mafjar (Jerico), the Dome of the Rock (Jerusalem) and the Great Mosque (Damascus). The adoption of a tailor-made analytical approach allowed achieving remarkable outcomes on the base glass and the colouring agents. Framing data in the broaden scenario of mosaic glass tesserae consumption and supply in the eastern Mediterranean basin, preliminary hypotheses on models for the manufacture and trade of glass tesserae under the Umayyad are discussed and evaluated. Apart from the archaeological relevance of the analysed assemblages, research has also shown how the application of a tailor-made protocol on mosaic glass tesserae can be the starting point for further enhancing our knowledge of this (and still fragmentarily investigated) material category.