Unveiling Ancient Maritime Secrets Trough X-Ray Computed Tomography (Ct): Iron-Based Finds From The Archaic Shipwreck Of Giglio-Campese

In the 1980’s, the Island of Giglio (Tuscany, Italy) became the site of an extraordinary discovery: a shipwreck in the Bay of Campese, dating back to the early 6th century BC. Initially located by professional divers (about two decades earlier), it was through the meticulous excavation led by Mensun Bound, who would later become a prominent figure in underwater archaeology, that both the ship’s cargo and its structural remains were brought to light. Thanks to the extremely heterogeneous composition of the load of international scope, this archaeological find represents a break-through in understanding archaic trade networks across the Tyrrhenian Sea. As part of a wide-ranging multidisciplinary collaboration involving various institutions and experts, our team employed X-ray computed tomography (CT) to explore the mysterious history of the ship and, in turn, of our own past. Among the numerous remarkable samples, some highly corroded and splintered iron-based materials were analysed with a custom-designed CT system, suitable for both on-site and laboratory scanning. These fragments are characterized by degradation phenomena and a thick layer of concretions, making the original shape illegible and, therefore, also their function. Hence, two measurement campaigns were organised with the aim of reconstructing their original morphology and thus identifying the type of artifacts. The analyses were carried out in our X-ray imaging laboratory in Ravenna. The setup was equipped with a 200 kVp X-ray tube and a flat-panel detector with an area of approximately 19×24 cm², with 127 μm pixel size. Although both are mounted on translation axes that allow to cover an area up to 1.5 x 1.5 m², in most cases the samples fitted the detector's field of view, making their movement along X and Y directions unnecessary. The objects are held and slowly rotated by means of a solid rotation platform, featuring a precision high-load rotary stage. In this configuration, more than 20 tomographic scans were performed with a voxel size of about 100 μm, resulting in a massive amount of data. While calcareous incrustations can be virtually removed, it has not yet been possible to define with certainty the type and function of the investigated artefacts. Some hypotheses have been proposed based on the profiles, mostly of quadrangular section, originally occupied by the metal, now entirely or almost entirely consumed by corrosion, leaving only a layer of mineralized concretion containing little to no metallic core. To support our investigation, complementary X-ray fluorescence analyses (XRF) were performed on specific points of the finds allowing us to determine also their elemental composition. Although what remains of these objects found in the depth of the Tyrrhenian Sea is just a “ghost” of the original ones, our CT examination, together with visual inspection and XRF results, contributed to throw light on ship’s cargo composition of Greek and Etruscan origin and on its route’s stages.