This illustration shows that the rock dubbed "Bounce" near the Mars Exploration Rover Opportunity's landing region at Meridiani Planum is not made up of the same minerals as surrounding soil. Spectra from three soil samples taken outside of "Eagle Crater" are compared to that of Bounce (bottom). The dashed white line in the center of the spectra indicates where the "fingerprint" for triple-oxidized iron (Fe 3+) occurs. While the soil samples possess this feature, Bounce does not. The results suggest that Bounce did not originate in the plains of Meridiani Planum. These spectra were taken by the rover's Moessbauer spectrometer. Measurements of Bounce were made on sol 67.