Further analysis of silica on Mars

In May 2007, NASA's Mars rover Spirit found that Martian soil has a high concentration of silica. This is considered as very strong evidence that water could have existed on ancient Mars, because certain hydrothermal reactions are most likely to produce silica. The discovery was announced in brief at the time (see http://www.nasa.gov/mission_pages/mer/mer-20070521.html), but scientists led by Professor S. Squyres (Cornell University, United States) have now had time to fully analyze the mineral deposits. In addition to the Miniature Thermal Emission Spectrometer (Mini-TES), the Alpha Particle X-ray Spectrometer (APXS) contributed significantly to the analysis. Analysis of the elemental composition of the deposits revealed that Si is strongly enriched relative to typical soil, and there are weaker enrichments in Ti, Cr, and Zn. Other major elements appear to be depleted. For more information, see the paper, "Detection of Silica-Rich Deposits on Mars", S. W. Squyres et al., Science, 320, 1063 (2008).