The path of Phlegraean pozzolana: from Puteoli to the whole Mediterranean basin

Phlegraean pozzolana, called “pulvis puteolana” by M. Vitruvius Pollio in his famous “De Architectura” (I century B.C.) book, used to play an important role to produce Roman hydraulic mortars, capable of enhancing mechanical strength even in underwater conditions. This geomaterial was widely employed by Romans, as it has been found in different locations across the Mediterranean basin (ROMACONS Project, Oleson et al., 2004). This study investigates the provenance of pozzolana used in Roman mortars by comparing different pozzolana samples collected from quarries in the Campi Flegrei area, which were historically well known by Romans, with pozzolanic aggregates found in hydraulic mortars from both Campanian archaeological structures and extra-regional sites such as Venice (Dilaria et al., 2024), Aquileia (UD) (Dilaria et al., 2023b), the Temple of Nora in the Sardina region (Dilaria et al., 2023a) and Soli Pompeiopolis in Turkey (Stanislao et al., 2011). The pozzolana samples were analyzed using a multi-analytical approach, to obtain chemical and minero- petrographic information through Polarized Optical Microscopy (POM), X-Ray Powder Diffraction (XRPD), Field Emission Scanning Electron Microscopy coupled with Energy-Dispersive X-Ray Spectroscopy (FESEM- EDS) and Laser Granulometry. By comparing mineralogical and chemical results of the analyzed samples with the literature data regarding the ancient mortars pozzolanic aggregates, this research presents preliminary results aiming to understand if there are compositional differences among aggregate fractions found in mortars from different sites and, eventually, if there was a preference regarding the exportation of a pozzolana from specific location. This research could serve as a reference database to further our knowledge of ancient Roman technology.