Fig. 7. Spectral signatures of the composition thickness maps of the interior area shown in Fig. 5, with both (a, b, c, and d) uncorrected PS-Io and (e, f, g, and h) CM-Io corrected spectra. Spectra (a) and (e) refer to mineral and pore space signatures, respectively. Spectra b and c show elevated optical density as a result of absorbance by mineral matter. Residual errors for the fitted spectra e, f, g, and h are shown with their root variance, .