Egyptian red gold

Red surface colorations frequently found on ancient Egyptian gold objects have been examined by x-ray diffraction (XRD), energy-dispersive x-ray spectroscopy (EDXRS), and other methods. The results indicate that these colorations are most often associated with tarnish films in which the predominant species is a silver gold sulfide (AgAuS), occurring on a substrate gold silver alloy. Another silver gold sulfide (Ag 3 AuS 2 ) may also be associated with these alloys and especially with those of higher silver content. These results have been corroborated by the synthesis of visually similar tarnishes on gold silver alloy coupons that have yielded analytical results identical to those obtained for the archaeological material.