Tidbits have come in, the phrase water-rich fluids has appeared more than once now on the JPL site. With reference to the rock Sabre, recently RATed, it has this to say: "Scientists speculate that this relatively soft rock (compared to others analyzed by Spirit) may have been modified by water. Small cracks in the surface outside the drill holes may be the result of interactions with water-rich fluids."<br /><br />Pot of Gold was said to have contained pyroxene and olivine. These are minerals that form at high temperatures, often from magma. However, it also contained hematite, and speculation on both the JPL website and others is that it was a basalt that was significantly altered by water or "water-rich fluids." In the process, some of the rock was altered to form iron oxide (hematite). This cannot explain why Sabre was so soft, because olivines, pyroxenes, and hematite all tend to be hard minerals.<br /><br />I should also mention that a trench made by Spirit as it approached the Columba Hills was examined with the Mini-TES, and the spectra have been interpreted as indicating kieserite, an evaporite that was seen in some abundance at Eagle Crater. It was suggested that subsurface water had risen and deposited this sulfate near the surface.