Where did Roman masons get their material from? A preliminary DRIFTS/PCA investigation on mortar aggregates from X Regio buildings in the Veneto area (NE Italy) and their potential sources

In this work preliminary results are presented of an on-going investigation aiming to identify the possible material sources employed by ancient Romans in their building activity in the X Regio, the European region corresponding to present north-eastern Italy and Istria (Croatia and Slovenia). The 63 - 420 m fraction of the aggregate component recovered from eleven mortar fragments of buildings located in the Veneto area (in or close to Lio Piccolo, Vicenza and Padua) is studied by diffuse reflection infrared Fourier transform spectroscopy and compared through principal component analysis to samples collected from local potential sources of raw materials. In this regard, the investigated samples from Lio Piccolo present a distinctive complexity, being this site located within the Venice lagoon, an area that has since been undergoing dramatic changes both due to natural and anthropic causes. The Vicenza and Padua sites were considered for comparison sake because they are or were located close to two rivers, the Bacchiglione and the Brenta, that in ancient times flowed into the Venetian lagoon. As expected, from the exploratory investigation reported here, no firm conclusions can be obtained for the mortar samples collected in Lio Piccolo, whereas the likely provenance of the aggregate component of the samples from Vicenza and Padova from the Bacchiglione and the Brenta riverbeds, respectively, is confirmed.