How archeometry can help history and geology: the case of the Geonoese towers in Capraia island?

The island of Capraia belonged to the Republic of Genoa from the XIVth century to the end of the XVIIIth century. During that period three towers and a fortress were built for defensive purposes. Concerning the building materials, it should be noticed that Capraia is a volcanic island, therefore lacking of carbonate rocks, which are essential for the production of lime. The literature reports that the lime arrived from Genoa and/or from Corsica while the sand seems to come from the beach of the port. This research reports the results of the study of the mortar utilized to build the towers with a particular focus on the provenance of the raw materials (lime and sand) and on the technology utilized to realize the mortar itself. As a matter of fact, in the mortar aggregate traces of metamorphic rock fragments peculiar of Northern Corsica, Gorgona and Western Liguria have been found, eventually interpreted as sand impurities of the beaches from where the transport boats (leudi) were leaving carrying goods from Corsica and Genoa. This is an example as how archaeometry can give information on the maritime trade routes of the north Tyrrenian sea and on the geology of the island.