The crystals in archaeological paintings can be analysed by scientists using diffraction. These studies, together with the findings of archaeologists, enhance our understanding of how they were made, as it was in the case of the Maya blue colour. This research can be used in educational workshops to prepare Maya blue and build palygorskite/indigo models in schools. Source: Institut Neel-CNRS and Lycée Pontcharra. Photograph from Bonampak, Chiapas, Héctor Montaño/INAH.