The key role of Pb-Bi, Pb-Te-Se and S-Fe-Te-Se inclusions, microstructures, and corrosion processes in reconstructing Etruscan metallurgy at Pyrgi (Latium, Italy)

The archaeological site of Pyrgi (Santa Severa, Rome, Italy) has yielded a diverse range of metal artifacts that provide valuable insights into the Etruscans' metallurgical knowledge and material selection practices. This study focuses on micro-inclusions, microstructure, chemical composition, and corrosive process of arrowheads, nails, and aes rude . Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), micro-Raman spectroscopy, and electrochemical analysis, i.e. , Voltammetry of Immobilized Particles (VIMP), and Mott-Schottky (MS) were used. The nails and aes rude are pure copper, with minor contents of tin and lead, while the arrowheads are ternary bronze alloy (Cu-Sn-Pb). The microstructures of nails and aes rude are characterized by the presence of Pb-Bi, Pb-Te-Se, and S-Te-Se-Fe micro-inclusions within the metal matrix, which provide insights into smelting processes, the nature of the ores used, and technological capabilities. The variability of inclusions suggests the use of polymetallic minerals as starting materials. Tellurium and selenium suggest refining practices and smelting techniques that were not fully optimized. The corrosion patinas are composed of cuprite, malachite, and trihydroxychlorides. The Mott-Schottky analysis highlighted variations in the electrochemical response of the corrosion layers, suggesting different alteration conditions among areas of Pyrgi. These results contribute to the exploration of Etruscan metallurgical choices and techniques, highlighting variations in smelting processes, raw materials, and processing practices.