High resolution neutron tomography as non-invasive tool for the study of a filigree from the Medieval Chiaravalle Cross

The Chiaravalle Cross, an ancient Italian processional cross from Chiaravalle Abbey (near Milan, Italy), is a jewellery masterpiece richly decorated with precious metals applied by combining different metalworking techniques like chiselling, engraving, gilding by laminas and amalgams. In particular, a golden filigree adorns the entire cross. A very small portion of this filigree has been made available for analyses, after the restoration in 2016. The filigree has a multi-component structure, made of drawn and after twisted silver wires, soldered and finally gilded. A neutron tomography imaging experiment has been carried out to disclose the three-dimensional structure of the ancient golden decoration for a comparison with two-dimensional results obtained by a previous SEM (scanning electron microscopy) investigation to demonstrate the potential of a non-invasive technique for a comprehensive understanding of the manufacturing technique.