Raman investigation on pigeonite in ureilite

The Raman spectra of 10 samples containing the mineral pigeonite, a Ca-poor P21=c pyroxene, were measured. Seven of the studied samples come from the achondritic meteorites belonging to the family of ureilites, two are from volcanic rocks, and one is synthetic. The studied samples have an mg content between 52 and 100. The differences in Raman spectra with C2=c and Pbca pyroxenes are highlighted; changes in peak position with mg of the major peaks at 340 and 670 cm-1 are significantly lower in C2=c compared to Pbca and P21=c pyroxenes. Peak width in natural pigeonite is higher than in synthetic one, owing to the defective texture of the former. The present results may provide a basis for in situ characterization of pyroxenes by means of Raman spectroscopy of planetary bodies in space exploration.