Chronology of early Islamic glass compositions from Egypt

Compositional data of archaeological glasses offer an opportunity to trace the movement of materials in the ancient and medieval world. The lack of a comprehensive record of well-dated samples from Egypt, one of the major producers of glass throughout the first millennium CE, has limited the systematic application of a chronological and geographical model. Here, we report LA-ICP-MS results of Islamic glass weights and stamps from Egypt that provide a precise record of high temporal resolution of glass compositions from Abd al-Malik's monetary reform in 697 CE to the year 1020 CE. This period covers several radical changes in Islamic glass making. After a significant hiatus in the production of glass weights between the last quarter of the ninth and the middle of the tenth century we see the advent of novel glassmaking recipes based on the use of soda-rich plant ash. Our study establishes a temporal model that serves as a tool for dating archaeological glass assemblages, as well as a geographical model that allows for a clear classification of Levantine and Egyptian plant ash glasses.