Terracotta mould and bronze dagger from Grotta dei Baffoni (Genga – AN): analysis, replica and interpretation

Abstract

A recent revision of the stratigraphic sequence and the finds from the excavations by Anton Mario Radmilli in 1952 and 1954 in the Grotta dei Baffoni Cave near Genga, included also a particular object consisting of a ceramic block with a sub-trapezoidal concave gouge readily identified by Radmilli as a clay mould used for metal melting, which, in fact, contained metallic droplets attached to its surface. It represents an unicum for both its typology and the results of our preliminary archeometric analyses, which sheds some light on the early copper metallurgy in Italy. The terracotta mould was found during the excavation campaign of 1954, in which Radmilli enlarged Trench B already excavated in 1952, in a not-better specified lower anthropic level, from 2.30 to 2.80 m depth (cultural level E), which, according to Radmilli’s stratigraphy, includes horizontal cuts n. XV, XVI, and XVII. Osteological finds from this level were recently radiocarbon-AMS dated to 3,640-3,430 yr cal BCE. Here we present the results we obtained from the analysis of replicas of the clay mould, which allowed us to identify the function of it as a cast for manufacturing small metal ingots. Geochemical SEM-EDS analyses on one metallic droplet detached from the surface of the mould, yielded a maximum composition of 92 wt.% copper (Cu), and 8-12 wt.% zinc (Zn), along with traces of silver (Ag). Thus, the metal appears to be a compound of copper and zinc but not an intentional alloy of the two metals, which can be obtained by smelting sulfide minerals (i.e., Fahlerz) such as tetraedrite-(Zn) or tennantite-(Zn). We interpret this Cu-Zn compound as the result of the work by a metallurgist who utilized the Grotta dei Baffoni Cave as his workshop during a period between the latest Cupper Age (Eneolithic), and the earliest Bronze Age. The interpretation of the results from our metallurgic analyses in the light of what it is known about the early copper metallurgy in Italy, are consistent with this chronological assessment. The experimentation also concerned the bronze dagger to verify a possible relationship with the clay mould, although coming from very different depth.