|Water of Mars! Maybe. The blue color is suspected to be pyroxene, which is some kind of mineral.|
"The image is produced by draping an orthorectified (Infrared-Red-Blue/Green(IRB)) false color image (ESP_030570_1440) on a Digital Terrain Model (DTM) of the same site produced by High Resolution Imaging Science Experiment (University of Arizona). Vertical exaggeration is 1.5."
Credits: NASA/JPL/University of Arizona