Archaeometallurgical Analyses of materials from Vetricella: preliminary results

Many fragments of iron slag have been found during surface surveys at Vetricella. Most of them, according to their typical plane or plano-convex shape – could be interpreted as smithing slags, and are constituted by variable proportions of fayalite (Fe2SiO4), wüstite (FeO), magnetite (Fe3O4), iron oxyhydroxides and quartz.

A few small iron bars have also been recovered: metallic iron is still present in the bar core, surrounded by a thick patina of alteration products (magnetite, maghemite and iron hydroxides:  XRD analysis). They could represent the final products of smithing activity.

Lead casting remnants and scraps are relatively common at Vetricella. SEM/EDS analyses revealed the presence of small (5-6µm) and abundant segregations of Cu-Sb-As

The most interesting finding is undoubtedly is a small ingot of copper and lead (with silver), semi-rounded in shape. SEM-EDS analyses (average of 4 raster scanned areas) indicate Cu/Pb ratio of about 4:5 by weight. In addition to metallic copper and lead, SEM-EDS analyses evidenced the presence of abundant, small segregations of Cu-Ag-S.  An intriguing hypothesis is that this ingot represent a sort of liquation cake from smelting of Cu-Pb-Ag ores like those known to occur in the nearby Colline Metallifere area.