ARCHAEOMETRIC STUDY OF THE HELLENISTIC METALLURGY IN SICILY: MINERALOGICAL AND CHEMICAL CHARACTERIZATION OF IRON SLAGS FROM PUNIC PANORMOS (PALERMO, ITALY)

Abstract

Archaeological excavations carried out in the town of Palermo revealed important traces of metallurgical activity related to the Punic Panormos. Five samples of iron slags, recovered during the digging, were characterized by micro-structural, mineralogical and chemical investigations as well as by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction and X-ray fluorescence. The studied remains are spongy, rust colored, with a plano-convex shape and their textural and mineralogical features suggest they are metallurgical slags produced during smithing process. Wüstite, magnetite, fayalite, kirschsteinite, hedembergite, cristobalite and quartz are the main identified mineral phases, while goethite, lepidocrocite and calcite occur as minor secondary phases. The iron slags show heterogeneous structures such as hammering clues, layering in wustite crystals and presence of calcium-rich minerals which are consistent with a broad variation of the forging temperature due to the use of different smithing techniques. This assumption is confirmed by the different crystallization temperatures of the detected mineral phases. Skeletal and dendritic shapes are indicative of rapid cooling and, possibly, quenching. The chemical composition is dominated by iron, silicon and calcium and it is almost constant for all the samples suggesting that they were produced with similar raw materials and technology. The high Ca content suggests the use of carbonate-bearing rocks, widely outcropping over the Palermo territory, probably exploited as fluxing ores for the metallurgical process. The multidisciplinary approach adopted in this study provided new data for a better understanding of the metallurgical techniques evolution in the Sicilian territory in ancient times. Since the studied iron slags represent the unique traces so far known of metallurgical activity in the ancient Palermo town, our results open interesting perspectives for future study of metallurgy in ancient Sicily.