Archaeological volcanic glass from the site of Rocchicella (Sicily, Italy)

The site of Rocchicella, near Catania, in eastern Sicily, has yielded important archaeological evidence from prehistoric times to the Middle Ages. Extensive archaeological investigations of cultural layers dating from the Palaeo-Mesolithic to the Copper Age have recently been undertaken, and volcanic glass, mainly obsidian, has been collected in the course of excavation. To determine the provenance of this volcanic glass, a non-destructive elemental analysis was carried out to measure the concentration of characteristic trace elements. The analysis was carried out using a new XRF spectrometer equipped with a beam stability controller and a quantitative method developed at the LANDIS laboratory of the INFN-CNR Institutes of Catania. In addition to the obsidian, it was demonstrated for the first time that a local vitreous material similar to obsidian, but displaying a completely different composition, was used during all the investigated periods. This material was identified as a basaltic glass, characterized by a superficial product of devitrification called palagonite. Analysis of the obsidians has led to the identification of the island of Lipari as the provenance source. High- and low-power microscopic use-wear analysis on obsidian and basaltic glass artefacts indicated that soft wood and plant matter might have been processed at the site.