Petrogeochemical approaches to the characterization of obsidian derived from Nychia area (Milos Island, Greece) using combined methods.

• Focus οn the obsidian source cropping out in Nychia area of Milos Island providing new analytical data useful from geological and archeological perspective. • A suitable methodology for an integrated obsidian characterization is proposed by combining Polarized light Microscopy, XRPD, SEM-EDS and portable Raman analysis. • Characterization of the most homogeneous vitreous part of obsidian samples ("amorphous phase") promoting further their fully description. In this study obsidian samples from "Nychia" area of Milos Island (Greece) have been analyzed and characterized with various analytical techniques including polarizing microscopy, XRPD, SEM/EDS, ICP-MS and Raman Spectroscopy. The studied samples have a rhyolitic composition. Microliths (feldspars, silica oxide phases, hornblende, biotite and opaque minerals), constituting the well-defined crystalline phases, are surrounded by a glassy matrix, which constitutes an equally defined "amorphous phase". In terms of texture, samples were divided into two groups, a healthy one and a partially devitrified one exhibiting perlitic texture, indicating the effect of locally different volcanic processes in the same narrow area. Furthermore, focused investigation relative to the microchemistry of the "amorphous phase" of the studied samples revealed that these data have satisfactorily discriminated the natural glasses of Nychia Milos source in Mediterranean area. Such results could also be used as the basis of a flexible method useful for trans-disciplinary problems dealing with the origin of obsidian artefacts. The Raman spectroscopy results of the Nychia samples offered insights into the use of the technique as a reliable nondestructive sourcing analytical tool. Moreover, the potential for a multifarious characterization of the glasses enhances further the geological research as well as the archaeological provenance issues of obsidians. [ABSTRACT FROM AUTHOR]