Study of ancient metal samples from Valle delle Forme

Valle delle Forme (Brescia, Northern Italy) is an archaeological site where ongoing excavations have given back a smelting plant of iron minerals, a forge for elaboration of semi-finished products, but also an “archaic” blast-furnace, and it could represent the “missing link” testifying the evolution from the bloomer to the blast furnacies techniques in iron production in northern Italy. A series of findings (iron based nails) have been studied combining different techniques. The nails, dating back to the 1300-1400 AD, present a heavily corroded surface. In order to infer indications on the inner part too, with the benefit of a non-destructive technique, we first performed a neutron based characterization concerning mineralogical phases, through a neutron diffraction study ran at ISIS. However, lacking in position sensitivity, we combined this study with Raman and SEM analyses too, in order to assign different mineralogical phases to different regions of the nail samples: yet, the inner part of the nails contains several different mineralogical phases, as it is evident from optical microscopy, and many indications can be derived about the production technology from the attribution of these mineralogical phases. Combining neutron, SEM and Raman analyses resulted in a twofold advantage. First of all, we could map the inner part of the nails as a function of the mineralogical phases. In addition, this mapping provided a sort of calibration for a better interpretation of the neutron diffraction patterns, used also for the nails that were not studied by SEM or Raman. This will be of benefit of further non destructive characterization in archaeometallurgy.