Archeometallurgical and technical characterization of 7th century AD iron fishing-spear and fire basket found in the Dor lagoon, Israel

An archeometallurgical and technical characterization of a Late Byzantine-Early Islamic fishing-spear (harpoon) and a fire basket, both made of iron, was performed. These fishing instruments, probably belonging to a fishing vessel dated to the seventh century AD, were retrieved from the Dor (Tantura) lagoon, Israel. The present research aimed at determining the composition, microstructure and mechanical properties of the objects in order to understand their manufacturing process. The objects were studied archeologically and typologically and by archeometallurgical minimally destructive testing methods. These included identification of forge welding lines, radiographic testing, metallographic light and SEM/EDS microscopy and microhardness tests. The results revealed a heterogeneous microstructure containing allotriomorphic, idiomorphic and Widmanstätten ferrite and pearlite, as typical to low-carbon wrought-iron manufactured by the bloomery process, along with some scattered inclusions. It is suggested that both objects were manufactured by a skilful blacksmith using a hot-working technique, with no evidence of carburization or quench-hardening processes. A detailed description of the assembly processes of both artifacts by forge welding, riveting and folding is proposed. The similarity in the chemical composition and the use of the same fabrication techniques suggest that both items were produced using the same raw material and were most likely fabricated in the same blacksmith workshop. This information extends our knowledge of metallurgical technologies and materials use in the Eastern Mediterranean during the Byzantine and early Islamic periods.