Fig. 8

Near infrared FORS spectra in reflectance mode from all of the analyzed colors, crossed with our calcium carbonate and gypsum reference ground layers. The characteristic gypsum bands were identified as the corresponding ground layer

Near infrared FORS spectra in reflectance mode from all of the analyzed colors, crossed with our calcium carbonate and gypsum reference ground layers. The characteristic gypsum bands were identified as the corresponding ground layer