Fig. 3

Paint cross-section from a dark blue tone from right (shadow) side of blue headscarf (sample 42). a Sample location, b LM image, dark field, c UV-induced fluorescence. d Corresponding SEM backscattered-electron image. The sample was further polished for the data shown in e–m, and therefore do not correspond exactly to a–d. The EDX maps were done last. e detail SEM backscattered-electron image, EDX maps of: f sodium, g aluminium, h silicon, i calcium, j potassium. µ-FTIR-ATR analysis: k distribution map of the 972 cm⁻¹ band characteristic of lazurite, l 872 cm⁻¹ band characteristic of chalk, m 1114 cm⁻¹ band characteristic of gypsum