Non-Invasive Chemical Analyses on Byzantine Copper Alloy Doors in 11th and 12th Century Italy

For the first time, chemical analyses by XRF of all Byzantine copper alloy doors in Italy from the 11th and 12th centuries are presented, compared, and interpreted. Three main alloying groups were detected for the eight doors: leaded bronze (Montecassino), leaded brass (Monte Sant’Angelo, Amalfi, San Paolo fuori le mura, Venice SC), and quaternary alloys (Atrani, Salerno, Venice MD). This leads to the conclusion that Byzantine workshops used different alloys for their production. The different alloying groups cannot be associated with specific, single workshops in Byzantium; also, we cannot exclude the production of specific doors in the same workshop. Together with the ability to date some of the doors by means of inscriptions or historical records this allows new hypotheses to be formulated regarding workshop processes. This research also presents, for the first time, color illustrations of the figuratively decorated backs of the Montecassino door.