Spectrum Vis-NIR reflectance spectrum of a thick layer of Beauregard pigment (PIG_0174_A_902) painted on limestone block Spectrum Vis-NIR reflectance spectrum of limestone block Spectrum Vis-NIR reflectance spectrum of a very thin layer of Beauregard pigment (PIG_0174_A_902, grains < 160 µm) painted on brown-grey limestone chip Spectrum Vis-NIR reflectance spectrum of brown-grey limestone chip