Just a feeling based on the fractures, that's why I put it out there and asked the question. When we've seen mineral filled fractures in rocks on Mars the fractures have usually been in fairly straight lines following the crystalline structure in the host rock, or at separations of the sedimentary layers. It could be an optical illusion, but many of the fractures are far from straight in this target, almost like series of large crystals in a honeycomb like arrangement. The appearance of sandstone could just be a dust covering. Appreciate the feedback :)

Looking forward to hearing how the team call this float rock :)

Edit: fixed typo