Tracking trachyte on the Roman routes: provenance study of Roman infrastructure and insights into ancient trades in northern Italy

Roman colonization of northern Italy during the late Republican Age brought a significant building activity in the new acquired territories, especially involving the construction of new infrastructure, which demanded huge amounts of stone. Trachyte of the Euganean Hills was one of the most used materials for building infrastructure, in particular roads, and even bridges, forum squares and aqueducts. This paper addresses the recognition of the provenance quarry of Euganean trachyte used in Roman public infrastructure in northeastern Italy, mostly built from the 1st Century BCE to the 1st Century CE. Petrographic features and major- and trace-element composition of bulk rock and phenocrysts, analyzed by XRF and LA-ICP-MS, were used as provenance tracers. The provenance determinations allow exploring the management of trachyte quarries and the development of extraction activities in the Roman times, as well as the related commercial and economic dynamics involving stone supply for public works. Moreover, indications are given with regard to the territorial organization of Roman settlements, their areas of political influence and ownership and competition of quarries. Finally, broad insights into ancient trades in northern Italy and the main routes of stone circulation are provided.