The Presence of Antimony in Some Grey Colours of Three Paintings by Correggio

This paper describes analyses that were performed on three canvas paintings by Correggio, the 'Danae', the 'Compianto sul Cristo Morto' and the 'Martirio di Quattro Santi', with special regard to the grey colours. Non-destructive XRF measurements showed that the elemental composition of these colours included non-negligible amounts of antimony, and that its abundance was related to the darkness of the colour. Optical microscope, SEM and EPMA analyses, carried out on a single sample taken from the 'Danae', confirmed that antimony was associated with the grey layers of the stratigraphical section and allowed us to hypothesize the presence of stibnite, which is a lead-grey coloured antimony trisulphide.