This image shows iron/magnesium-bearing hydrated minerals called phyllosilicates in a white/yellow color. Phyllosilicates are clay and clay-like minerals formed by chemical reactions with liquid water. They are very thin (microscopic) stacked layer crystal forms, also called sheet silicates. The CRISM team took this image to characterize surface hazards in preparation for the Mars Science Laboratory (Curiosity) rover mission…. [More at link]
More CRISM images.