An international team of scientists from France, the Netherlands and the United Kingdom has found a singular mixture of strongly saponified oil with high lead content and a lead white pigment in a microsample from the ground layer of Leonardo da Vinci’s Mona Lisa. The most remarkable signature in the sample is the presence of plumbonacrite, a rare compound that is stable only in an alkaline environment. The Mona Lisa, by Leonardo da Vinci. Many...