Basilica of San Marco (Venice,Italy/Byzantine period): Nondestructive investigation on the glass Mosaic Tesserae

Some tesserae of San Marco Basilica (Venice) have been investigated in order to understand the possibilities of non-destructive investigation in the study of glass mosaics. In particular, the tesserae belonging to a mosaic piece coming from the Baptistery (dated about 1340) have been previously investigated by optical microscopy (table and portable) and divided in groups according with their optical appearance. Then the results have been compared with PIGE-PIXE, p-XRF, XPS data and elaborated by PCA. The results show that green tesserae and the “cartellina” (both characterised by low cromophore amounts) can be difficultly studied by portable instruments. On the other side, the red tesserae, although similar from the optical point of view, do not always show the same composition.