Evidence of open-air late prehistoric occupation in the Trieste area (north-eastern Italy): dating, 3D plaster characterization and obsidian provenancing

Abundant clay burnt plaster remains and a few flaked tools, including an obsidian artefact, found on surface not far from Trieste (north-eastern Italy) provide a rare evidence of a possible prehistoric open-air occupation in the area. To confirm and detail their ancient origin, a plaster sample has been dated via thermoluminescence, giving an age between 4000 and 2000 BC. Outer and inner structure of selected plaster samples has been characterized using several techniques, i.e. X-ray diffraction, scanning electron microscope and X-ray computed micro-tomography, obtaining information about their production technology. The last technique has allowed to image and virtually extract vegetal remains and imprints. Their 3D morphological study has contributed to collect information about the ancient environment and has provided clues to define the plaster production season. The Lipari Island provenance of the obsidian artefact, revealed by PGGA, suggest that the site was part of long-scale connection systems and probably acted as intermediary between north-eastern Adriatic coastal areas and inner Karst plateau.