Fig. 2

Paint cross-section from a bright blue tone from right (shadow) side of blue headscarf (sample 41). 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–l, o–r, 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 sulphur, j potassium, k calcium, l magnesium, and EDX spectra of: m lazurite particle, n chalk particle. µ-FTIR-ATR analysis: o FTIR-ATR spectra belonging to lazurite, chalk, gypsum, p distribution map of the 978 cm⁻¹ band characteristic of lazurite, q 870 cm⁻¹ band characteristic of chalk, r 1110 cm⁻¹ band characteristic of gypsum