Mossbauer Spectrometer. Because many of the most important minerals on Mars contain iron, the Mossbauer Spectrometer is designed to determine with high accuracy the composition and abundance of iron-bearing minerals that are difficult to detect. Identification of iron-bearing minerals yields information about early martian environmental conditions. The Mossbauer Spectrometer is also capable of examining the magnetic properties of surface materials and identifying minerals formed in hot, watery environments that could preserve fossil evidence of martian life.
Source: NASA, Cornell University, The Mossbauer Spectrometer Electronics