Spectral signatures of distinct units in CRISM image FRT000134D2. Dotted curves show CRISM I/F spectra, and solid lines show laboratory spectra from the Bishop collection and the RELAB spectral library. (a) Units 3a and 3b compared to a laboratory spectrum of opal-A (BKR1JB0632b from Kilauea, HI; J. L. Bishop et al. 2024); dashed lines mark diagnostic absorption bands. (b) Unit 4 compared with a hypersthene spectrum (C1SC36; Cloutis, 2002) in blue. Locations of units 3 and 4 are shown among the ROIs mapped in Figure 5(c).