Through a Glass Brightly: Islamic Glass Inlays in the Convent of Santa Fe in Toledo (Spain)

The Islamic era left a lasting legacy in the visual and material culture of the Iberian Peninsula. This phenomenon is particularly striking in a rare find of architectural fragments of an arcade with horseshoe-shaped arches in the convent of Santa Fe in Toledo (Spain). Different coloured glass-inlays (turquoise, purple, colourless) were embedded in the iconographic bas-relief made of plaster, an artistic technique that is unparalleled. This study explores the dynamics of glass supply and workshop practices in 11th-century Spain through the chemical analysis of 46 specimens of these glass inlays. Laser ablation inductively coupled plasma mass spectrometry revealed a compositional resemblance but no identity with Iberian soda-rich plant ash glass, pointing to a regional or even local production. The glass assemblage as a whole proved very homogeneous and we were able to identify possible batches in which the individual pieces were probably cut from the same sheet of glass. Despite using the same base glass, the copper-turquoise coloured fragments showed different colouring techniques and combinations of colouring elements. Our findings shed light on the organisation of secondary glass working and material procurement for artistic purposes in Islamic Spain.