Early copper Alpine metallurgy

A few of the oldest Alpine copper objects, dating from the Late Neolithic and the Early Copper Age of the Italian Eastern Alps (Alto Adige and Trentino), have been analyzed in order to interpret the manufacturing processes. Conventional metallographic analysis using optical microscopy with reflected light was employed to investigate two copper fragments from Isera La Torretta, Trento. State-of-the-art techniques of crystallographic texture analysis using neutron powder diffraction were used to study three copper axes from Alto Adige: The copper axe of the Iceman, and those from Castelrotto and Colma, Bolzano. The results of the experiments allowed full interpretation of the metallurgical techniques. The copper objects from Isera were rolled from sheets of native copper that had previously been slightly thinned at room temperature. The Iceman and the Colma copper axes were cast into bivalve molds and never underwent significant hot or cold working. The copper axe from Castelrotto shows a marked cube texture deriving from extensive recrystallization due to cold working followed by high temperature annealing. All three axes are presently in the softened state. Neutron diffraction texture analysis proved to be an excellent innovative technique for the totally non-invasive metallographic analysis and interpretation of thick metal objects.