The effect of surface texture on the mineralogical analysis of chondritic meteorites using Raman spectroscopy

Raman imaging on different types of meteorite surfaces was performed. Three different surface textures on a chondritic meteorite from the Dhofar 005 strewnfield and a fourth surface with a very rough texture on a goethite mineral have been investigated. The Raman measurements were made with and without autofocus. The influence of the surface texture on the quality of the Raman spectra was analyzed. The percentage of the informative Raman spectra obtained from every sampled area were sufficient to assert the local mineral composition. For obtaining a spatial distribution of minerals (in the micrometer range), an autofocus device needed to be employed. It was found that approximately 85% of all Raman spectra taken at λext=633 nm show sufficient information to establish a clear assignment to a certain mineral. In the case of the rough goethite surface, measured without an autofocus device approx. 60% of the recorded spectra could be assigned.