| Abstract: | Ancient mosaic glass tesserae sampled from archaeological sites located in the Mediterranean area have been analysed by Inductively Coupled Plasma‐Optical Emission Spectroscopy (ICP‐OES). The aim of the research was to understand the role played by 3d transition metals in the optical properties of such samples. In order to better identify the specific effect of the main chromophorous element, modern samples have been prepared in the laboratory by adding to a colourless base frit controlled concentrations of colouring oxides. Samples with compositional and optical properties similar to the ancient ones have been obtained. For all these modern samples, as well as for all the ancient ones, electron paramagnetic resonance (EPR) measurements have been performed. The features of the EPR spectra could be successfully associated with the presence and abundance of the paramagnetic colouring ions (namely iron, manganese and copper) and to their oxidation states. This could be a basic step towards understanding the provenance and chronological attribution of mosaic glass tesserae. |
