Located in the lowest elevation shaded side of a north polar Mars dune, at about 80 degrees latitude, this array of petaled and colorful material has never been seen anywhere else to date. The formation is related to the Araneiform or Spider patterns which dominate the dunes and ground level in this area near the defrosting seasonal ice cap. Image ESP_016032_2600, color, and IR grayscale. This location is related to the other enlarged sections displayed on twitpic in sequence, showing dark 'leaf' shapes, dark gullies, dark streaking, and dark fracture fill eruptions. There is some evidence of mounded vent type cones with depressed cores nearly in contact with this unusual detailed petal array crystallinity controlled structure.  This is somewhat similar to massive calcite crystalline petaled growths found in smaller size on Earth. This dark shaded face of the dune should establish this as recent or an exposed excavated fairly recent material. At subfreezing and wind protected conditions where dune driven infill should bury this, it is uncovered by an active process, or, formed and caused by a ongoing process of formation activity in the dark, cold, shade. Seasonal defrosting is underway. More at http://marsroverblog.com 
credits: source image, NASA/JPL/University of Arizona  HiRISE:  http://hirise.lpl.arizona.edu/ESP_016032_2600