Since landing in 2012, the Mars Science Laboratory (MSL) Curiosity rover has explored over 20 kilometers of Gale crater, climbing almost 400 meters in elevation. The fluvio-deltaic, lacustrine, and aeolian sediments in the crater have been well documented by Curiosity’s suite of in situ and remote science instruments. Indeed, they have traced chemical trends that track changes in lithology and diagenesis over the study area—though most instruments only sample individual rock, vein, and soil targets at a very small scale. The Mast Camera (Mastcam) has periodically acquired much larger (meter-scale) multispectral, visible to near-infrared observations of outcrops throughout this stratigraphic sequence, with the resulting spectra tracking iron-bearing minerals and oxidation states. These observations contextualize the precise chemistry measured by the other instruments, and allow interpretations about the landscape beyond the rover’s traverse. In this study, I present the first comprehensive analysis of the spectral variability observed in Gale crater’s rocks with Mastcam, from sol 750 (when Curiosity first entered the lacustrine deposits of the Murray formation at Pahrump Hills) through sol 2755. Characteristic spectral parameters can help distinguish Murray formation from Stimson formation, and also allows comparisons of spectral variations to changes in lithology; the Murray formation is highly variable, and spectral signatures are not always confined to member boundaries. Several of these spectral parameters are also measured by the Chemistry and Camera (ChemCam) instrument, which collects continuous spectra in passive mode from 400-840 nm. A quantitative comparison of the ChemCam passive and Mastcam datasets reveals that ChemCam’s higher spectral resolution does not significantly affect measured spectral variability. Mineralogical interpretations based on Mastcam spectra, under the lens of this cross-instrument calibration, are an essential component of the suite of observations needed to characterize the diverse geology of Gale crater
