Studying ancient Egyptian copper-alloy objects via X-ray diffraction and Machine Learning

The paper reports a novel approach to studying the manufacturing techniques of ancient Egyptian metal objects. The study approach was performed on 12 copper-alloy objects, the majority of which are metal vessels. They were part of the burial assemblage of the Theban Tomb (TT) 8, belonging to the ‘overseer of works at the Great Place’ Kha and his wife Merit, that was found undisturbed in 1906 in Western Thebes (Egypt). The funerary assemblage, dating to the mid-18th Dynasty (ca. 1425–1352 BCE) is currently kept at Museo Egizio, Turin (Italy). The investigation aimed to gather further information regarding the manufacturing processes and methods that were employed to produce the copper-alloy objects selected for analysis. The bronze vessels and stands are among the best and most sophisticated metal artefacts from New Kingdom Egypt in terms of their technology and preservation. Here, non-destructive and non-invasive X-ray fluorescence (XRF) data is reported, and X-ray diffraction is coupled with machine learning which allows one to define specific data clusters that are compared with the overall role of the objects from a historical perspective and its macroscopic features. We identified four main groups as a function of the metalworking methods, spanning from highly homogeneous microscopic structures induced by a high thermal treatment such as annealing to extremely nonhomogeneous microscopic structures compatible with cold metalworking. This classification from a microscopic point of view is successfully integrated with a macroscopic classification by shape, demonstrating a particular processing method for each intended design type and use.