Mineralogy of a Martian meteorite as determined by Raman spectroscopy

Using the Raman point-count procedure that we anticipate using in planetary surface exploration, we have identified and characterized the major, minor and trace mineral phases in rock chips of a Martian meteorite, EETA 79001. Raman spectra are shown for pyroxene, olivine, maskelynite (shocked, isotropized feldspar), chromite, magnetite, ilmenite, ulvöspinel, pyroxferroite, merrillite, apatite, anatase, an Fe sulfide, calcite and hematite. Raman spectra provide information on compositional variations of pyroxene, olivine and Fe-Ti-Cr oxides and modal proportions of the rock. The maskelynite-free mineral mode obtained on rough rock surfaces is consistent with modes obtained by optical microscopy on a thin section of lithology A of this meteorite. Compositions and variations in compositions of major silicate minerals (pyroxene and olivine) on the basis of Raman peak positions are consistent with those obtained in previous studies by electron probe microanalysis. The variations in composition of the silicate minerals represent different stages of crystallization during the formation of this rock near the Martian surface.