An unusual dark patina on Egyptian copper alloy objects in the royal Ontario museum collection

摘要

The unusual appearance of a dark patina on a select group of Egyptian copper alloy objects in the Royal Ontario Museum (ROM) collection has raised the question of both its composition and formation and therefore, its authenticity. The purpose of this project was to determine both the constitution of the patina and the process by which it was formed. A cross section sample from one artifact was analysed using optical, metallurgical and scanning electron microscopy in order to clarify the relationship between the patina layer and the body metal. In addition, energy dispersive spectroscopy was employed to establish the chemical composition of the body metal. Surface samples were removed from all the objects and subjected to x-ray diffraction in order to identify the crystalline compounds present. Fourier transform infra-red spectroscopy was used to establish the presence of any organic compounds in the surface samples. Although further analysis is required, the results of the research suggest that the patina may have been formed as a result of a modern cleaning treatment possibly followed by an artificial re-patination treatment.