Thermoluminescence and visible reflectance spectroscopy applied to the study of blue-green mosaic silica-glass tesserae

We report the results of a series of measurements of Thermally Stimulated Luminescence (TSL) and visible reflectance spectrometry (vis-RS) performed on several modern blue-green silica glass mosaic tesserae. They were produced from the same matrix with different additions of colouring and opacifying oxides to get a wide shadow of blue colorations. This study follows others previously performed on archaeological mosaics, and aims at the understanding of the TSL emission of this class of glasses, particularly suitable for dating. The usefulness of the combined techniques for the identification of the metal ions, responsible for the blue coloration in a given sample is confirmed as well as the positive role played by antimony in enhancing the TSL response. In general, however, the TSL characteristics of mosaic glasses depend on the glassy matrix and on its crystallisation degree rather than on the formation of colour centres associated to the introduction of colouring oxides. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.