Illuminating al-Gharb: LA-ICP-MS characterization of 10th- to 13th-century CE glass from Silves Castle, Portugal

Written sources indicate that Alexandria in Egypt was a leading producer of Roman glass. Furthermore, archaeological finds have provided evidence for the local production of drawn glass and gold‐in‐glass beads, which were distributed throughout the world. In this study, we present an analysis of the chemical composition of more than two hundred glass objects from the Roman (2nd–3rd/4th century ce) and Late Antique (4th/5th–7th century ce) glass bead workshops located at Kom el‐Dikka in Alexandria. This study is based on the results of portable X‐ray fluorescence (pXRF) analyses carried out on raw glass, bead semi‐products, products and waste from both periods. Additionally, the glass chemistry of some Islamic (8th–12th century ce) beads found at the site has been analysed.Despite the limitations of the method, the vast majority of samples exhibited compositions confirming their general dating and Egyptian origin. Remarkably, a single bead was made of high‐alumina glass and appeared to be an import from India, possibly a remnant of the Indo‐Pacific glass bead route that connected Red Sea ports and Europe in Late Antiquity. In addition, we offer a new analytical approach to the method that has potential to enhance the value of pXRF in the analysis of archaeological glass.