The production cycle of lime-based plasters in the Late Roman settlement of Scauri, on the island of Pantelleria, Italy

This paper deals with the archaeometric study of lime-based plasters found in the archaeological settlement of Scauri, located in the homonymous bay in the south-western part of Pantelleria Island. Since 1999, archaeological surveys have led to the recovery of the huge remains of a Late Roman settlement dating back to the fourth-fifth century AD. It is well known that the island of Pantelleria is entirely composed of volcanic rocks. Accordingly, the production of quicklime required calcareous rocks to be imported. Also, the selection criteria of the sandy aggregate are relevant and of interest to this study, to evaluate the achieved technological level. Within this context, a mineralogical and petrographic characterisation of the plasters was carried out using thin-section petrography, for the classification of the sand aggregate. Moreover, X-ray diffraction and scanning electron microscopy were performed to investigate the composition of the binder. The analytical results allowed the identification of different recipes for the manufacture of the studied plasters, obtained by the use of different types of aggregate (volcanic rock fragments, pumice, basaltic scoriae, and ceramic fragments) and highlighted the degree of pozzolanic reaction of the binder. Finally, the provenance of the calcareous raw material was inferred using a petrographic approach.