Surface compositions of the alloys before (columns on left) and after (columns on right) patination.

EDS analysis was carried out at 100X magnification (area of analysis: 1.3 x 0.8 mm). Each value is the mean of 3 measurements. Highlighted rows indicate the most common alloy compositions described in historical sources. The presence of oxygen before patination is likely due to the tarnish of the patinas in air occurred from the moment of the creation of the alloy to the day of the analysis.