Original story from NASA: <a href="http:&#x2F;&#x2F;www.nasa.gov&#x2F;feature&#x2F;jpl&#x2F;rocks-rich-in-silica-present-puzzles-for-mars-rover-team" rel="nofollow">http:&#x2F;&#x2F;www.nasa.gov&#x2F;feature&#x2F;jpl&#x2F;rocks-rich-in-silica-present...</a>