Metallographic analysis of 3000-year-old Kanalski Vrh hoard pendant

In a Late Bronze Age hoard at Kanalski Vrh in Slovenia, bronze pendants were found among numerous other artifacts. Among them a group of nine pendants of very similar compositions contained higher amounts of antimony, arsenic, nickel, cobalt, and iron, which suggested that speiss was added to bronze. Furthermore, most pendants had a silvery grey surface that differed from the common color of tin bronze, with about 13% Sn. One of the pendants was analysed by light optical and electron microscopy, Auger electron spectroscopy (AES), X-ray diffraction (XRD), and differential thermal analysis (DTA). Analyses revealed that the surface of the pendant was corroded, the copper alpha phase was eaten away, and the remaining eutectoid phase exhibited that silvery grey color. Comparison of chemical composition of the pendant and of compositions of speiss ingots found in the same hoard indicated that speisses could be used as alloying additions in making melts for casting pendants.