Chemists discover new lead(II) oxide pigments in the Mona Lisa and the Last Supper

Chemical analysis of Leonardo da Vinci’s Mona Lisa and the Last Supper reveals the presence of plumbonacrite and shannonite, rare lead compounds only stable in an alkaline environment. The ground layers of the paintings uncovered high lead content in several forms, with shannonite being detected for the first time in a historical painting.

A microsample from the white ground layer of the Mona Lisa was analysed using high-angular resolution synchrotron x-ray diffraction and micro-Fourier transform infrared spectroscopy, confirming the presence of lead white – a widely used lead-based white pigment, consisting of two main lead carbonates, hydrocerussite and cerussite. In addition, the diffraction pattern of plumbonacrite was faint but unambiguous, an unexpected result as this rare lead carbonate has not been reported in previous analyses of Italian Renaissance artwork.