In this study façon-de-Venise glass objects from several Portuguese archaeological sites were studied aiming at characterising their chemical composition, discussing the raw materials and possible provenance. These objects were found during four archaeological excavations performed in Portugal (at Santa Clara-a-Velha Monastery (SCV) in Coimbra, São João de Tarouca Monastery in Lamego (SJT), Miguel Fernandes Square in Beja (PMF) and at the courtyard of the University of Coimbra (CPU)). Most fragments are dated to the 17th century, with only two objects being dated between the 14th and 15th centuries. These last two fragments, due to chronological reasons, can't be attributed to a façon de Venise production, but were included in this study for comparison. The glass composition was characterised by means of particle induced X-ray emission (μ-PIXE), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and UV-Vis reflectance spectroscopy. All thirty-one objects are composed by soda-lime-silica glass and the use of coastal plants as raw materials is suggested by the contents of MgO, K2O, P2O5 and chlorine. The observed greyish/bluish glass hue was also investigated and UV-Vis analysis allowed one to identify Co and Fe as the cations responsible for that hue. Through the analysis of silica trace elements and of the flux agents it was possible to associate four objects, from the Santa Clara-a-Velha Monastery assemblage, to Venetian production (three objects of cristallo and one object of vitrum blanchum) and to identify two other distinct production lines. One group comprising fragments from São João de Tarouca Monastery, presented medium alumina contents, differing from known façon-de-Venise production centres. The other group includes most fragments from Miguel Fernandes Square assemblage and has high alumina values, which, once again, is not consistent with any of the known façon-de-Venise production centres. For these reasons, the existence of new façon-de-Venise production centres is proposed.
- Façon-de-Venise glass
- UV-Vis reflectance spectroscopy