It seems like that most of the geology discoveries reported by Arizona scientists are about Mars these days. I see that Carl Weitz with the Planetary Science Institute in Tucson, is one of the authors on a study in the November issue of Geology that found evidence of extensive hydrated silicas on Mars using Mars Reconnaissance Orbiter data.
The article was titled, "Opaline silica in young deposits on Mars" which has been widely reported as opals. The significance is that they usually contain 3-10% water, and require liquid water to form on Earth. That, plus the Martian hydrated silicas being only a couple billion years old, suggest a watery environment much more recent than thought.
[right, High-Resolution Imaging Science Experiment, Mars Reconnaissance Orbiter. Credit, NASA/JPL-Caltech/University of Arizona]