Non-invasive techniques for characterization of original Roman mosaic fragments

Abstract

Abstract In this study, it was reported the preliminary results on the chemical and structural composition of decorative elements remains from original Roman mosaic fragments collected from the Roman Mosaic Museum, Constanta (Romania). These investigations were carried out by using non-destructive and micro-invasive techniques such as optical microscopy, X-ray diffraction, field emission - scanning electron microscopy - energy dispersive X-ray spectroscopy, vibrational spectroscopy (i.e., FTIR and Raman). The studied fragments, apart from being beneficial to different restoration opportunities of this Roman mosaic, could be also included in its modification through air pollution. The major and minor phase components of the studied mosaic fragments were determined, the crystal structure of the main phases was analyzed, and their three-dimension spatial arrangement was reconstructed. The similar composition of the major phases of all mosaic fragments can indicate a generic recipe for making mosaic elements, but minor phases were presumably added for coloring of mosaic pieces. Some degradation areas inside the volume of the mosaic fragments were found by means of the X-ray diffraction method. The areas are probably related to the formation of iron hydroxides during chemical interactions of mosaic fragments with the sea and urban polluted atmosphere. The results can also offer important information about the original materials that were used in the Roman period.