New insights on the provenance of obsidian fragments of Ustica Island (Palermo, Sicily).

In this study we applied a multidisciplinary approach, coupling geophysical and geochemical
measurements, to unveil the provenance of 170 obsidian flakes, collected on the volcanic
island of Ustica (Sicily). On this island there are some prehistoric settlements dated from
the Neolithic to the Middle Bronze Age. Despite not having geological outcrops of obsidian
rocks, the countryside of Ustica is rich in fragments of this volcanic glass, imported from other
source areas. The study of obsidian findings was carried out first through visual observations
and density measurements. At least two different obsidian families have been distinguished,
probably imported from Lipari and Pantelleria islands. Analysing the magnetic properties
of the samples, these two main sources were confirmed, but the possibility of other
provenances was inferred. Finally, we characterized the geochemical signature of the Ustica
obsidians by performing microchemical analyses through electron microprobe (EMPA) and
laser ablation (LA–ICP–MS). The results were compared with literature data, confirming
the presence of the Lipari and Pantelleria sources (Sicily) and indicating for the first time in
this part of Italy a third provenance from Palmarola island (Latium). Our results shed new
light on the commercial exchanges in the peri-Tyrrhenian area during the prehistoric age.