Chemical characterization of obsidians from different Mediterranean sources by non-destructive SEM-EDS analytical method

The aim of our research is to check the SEM-EDS non-destructive analytical method for discriminating and locating the possible sources of obsidian artefacts. Moreover, in order to obtain a significant discrimination of Mediterranean obsidians, we analysed samples collected from outcrops of the major sources: Monte Arci (Sardinia) and Palmarola, Lipari, Pantelleria, Gyali and Melos islands. All samples were analysed by both XRF (whole rock) and SEM-EDS (glass and microliths-microphenocrysts). The XRF analysis reveals that major elements discriminate obsidian. The discrimination using major elements is very useful because the amount of trace elements is lower than the detection limit of a Si(Li) ED Detector. The major elements, particularly SiO2, Al2O3, CaO, Na2O and K2O, of obsidian glass discriminate the six main Mediterranean sources. Our work demonstrates, therefore, the possibility of discriminating different provenance of obsidian artefacts using SEM-EDS, by means of a relatively rapid, effective and above all non-destructive method.