Vera Rubin ridge (VRR) is a topographic high within the layers of Mount Sharp, Gale crater, that exhibits a strong hematite spectral signature from orbit. The Mars Science Laboratory Curiosity rover carried out a comprehensive investigation to understand the depositional and diagenetic processes recorded in the rocks of VRR. Sample Analysis at Mars (SAM) evolved gas analyses (EGA) were performed on three samples from the ridge and one from directly beneath the ridge. SAM evolved H₂O data suggested the presence of an Fe‐rich dioctahedral smectite, such as nontronite, in the sample from beneath the ridge. H₂O data are also consistent with ferripyrophyllite in VRR samples. SAM SO₂ data indicated that all samples contained Mg sulfates and some Fe sulfate. Several volatile detections suggested trace reduced sulfur sources, such as Fe sulfides and/or S‐bearing organic compounds, in two samples while significant O₂ and NO evolved from one sample indicated the presence of oxychlorine and nitrate/nitrite salts, respectively. The O₂ evolution was the second highest to date and the first observed in ~1,200 sols. HCl released from all samples likely resulted, in part, from trace chloride salts. All samples evolved CO₂ and CO consistent with oxidized carbon compounds (e.g., oxalates), while some CO₂ may result from carbonate. SAM‐derived constraints on the mineralogy and chemistry of VRR materials, in the context of additional mineralogy, geochemistry, and sedimentology information obtained by Curiosity, support a complex diagenetic history that involved fluids of a range of possible salinities, redox characteristics, pHs, and temperatures.

The present study investigated the removal of methylene blue (MB) and orange II (OII) dyes from synthetic wastewater by means of adsorption and photocatalysis using natural kaolins. ForMB adsorption, the raw kaolinite-rich samples showed the greatest adsorption capacity, with rapid uptake (90% after 20 min). The experimental results were fitted better using the Langmuir isotherm model parameters compared to the Freundlich model, suggesting that the adsorption corresponds to monolayer coverage of MB molecules over the kaolinite surface. For OII, neither the Langmuir nor the Freundlich model gave reliable results, because the adsorption of anionic dye molecules by the clayey particles is not favoured.Mixtures of kaolinite/Degussa TiO2 were also prepared, and their photocatalytic properties under UVlight exposure were investigated. Decolourization of MB solutions was observed, even in a mixture with low TiO2 content. This is related to the combined effect of adsorption and photocatalysis and, unlike the pure clay samples, the efficiency of such mixtures against OII was only slightly weaker (80–94%).For TiO2-impregnated clays, with the kaolinite layers separated by sol-gel TiO2 particles, the MB removal was slow and effective only after >24 h due to the complexity of the bonding of MB molecules. On the other hand, the removal performance against OII solutions was very efficient (nearly 100%) within only 2 h. This excellent performance was attributed to morphological changes in clay particles.