The Chemistry & Mineralogy X-Ray Diffraction (CheMin) instrument represents a major advancement in identifying martian minerals. After the rover prepares a rock sample, CheMin will then direct a beam of X-rays as fine as a human hair through the powdered material. Because all minerals diffract X-rays in a characteristic pattern and all elements emit X-rays with a unique set of energy levels, scientists will use the information from X-ray diffraction to identify the crystalline structure of materials the rover encounters on Mars.

These analyses will assist in the assessment of water history and the search for possible signatures of life. The instrument can identify and quantify all minerals in complex natural samples (including basalts) and soils.