Characterization and provenance studies of the stone tesserae from the “A Grandi Fiori” mosaic in the Roman villa of Casignana (Reggio Calabria, Italy)

This study focuses on the archaeometric analysis carried out on the stone tesserae constituting the "A Grandi Fiori" Mosaic in "Room N" of the residential area of the Roman Villa at Palazzi di Casignana (Reggio Calabria, Italy). The mosaic, dated to the 3rd century CE, features green and white tesserae arranged in four-petaled floral motifs. A multi-analytical approach was adopted to characterize both the green and white stone tesserae constituting the mosaic. In addition, provenance studies were conducted on the white marble tesserae. Data obtained from mineralogical and petrographic analyses using Polarized Optical Microscopy (POM), X-Ray Diffraction (XRD), and Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS) were combined. Furthermore, the determination of oxygen and carbon stable isotope compositions (delta 13C and delta 18O) through mass spectrometry (MS) was performed on the white marble tesserae. The results from these investigations were compared with the recently updated reference databases of major Mediterranean marbles used in antiquity in order to evaluate their most probable origin. The minero-petrographic investigation revealed the use of a biomicrite for the green tesserae. On the other hand, the petrographic and geochemical analyses of the white tesserae indicate the presence of marbles sourced from various regions, including Asia Minor, Greece, and Italy, with a predominant use of Proconnesian marble. The presence of mosaic tesserae sourced from distant Mediterranean areas further underscores the historical significance of the villa and provides new insights into the trade routes of raw materials in ancient Rome. At the same time, the evidence may suggest a possible reuse of marble leftovers, potentially related to the documented phases of structural transformation and renovation of the villa.