The role of opacifiers in the luminescence of mosaic glass: Characterization of the optical properties of cassiterite (SnO2)

Thermoluminescence (TL) and radioluminescence (RL) have been exploited to study the optical properties of a few glass tesserae of the baroque mosaics of the vault of San Pietro cathedral in Rome. Recent results gave evidence that the dosimetric properties of mosaic glass depend on the presence of microcrystals in the glass network. For the samples analyzed in the present study, taking into account their chemical composition and presence and type of crystalline inclusions, it was observed that those opacified with tin-based additives (in particular, cassiterite, tin dioxide) showed higher luminescence sensitivity, being therefore more suitable for dating applications. The correlation between the presence of cassiterite and the possibility of successfully evaluating the equivalent dose has been investigated.