This spectrum of the soil at the Mars Exploration Rover Opportunity's landing site, Meridiani Planum, shows the presence of the shiny green mineral called olivine also seen at the Mars Exploration Rover Spirit's landing site, Gusev Crater. Based on this data, scientists believe the soil at Meridiani is made-up of in part of finely grained basalt, a type of volcanic rock. The spectrum was captured by Opportunity's Moessbauer spectrometer.