Abstract. Earth-based and orbital spectroscopy and Viking Lander data strongly suggest that rocks on Mars are coated with indurated dust deposits. Rock coatings will influence mineralogical measurements to be acquired in situ from Mars rovers and other surface missions, in that most techniques will detect the coatings and/or coatings plus underlying minerals. In this paper, we present results of experiments on varnished basalt cobbles from the Lunar Crater Volcanic Field, Nevada, using laser Raman spectroscopic microprobe measurements obtained with a 514.5 nm Ar + laser and irradiation spot sizes For background, LRMS uses monochromatic radiation (i.e., a laser) as excitation and collects the radiation scattered from samples. The frequency of the scattered radiation is shifted relative to the laser in ways that are directly related to molecular vibrations in the sample (gas, liquid, and solid). Any given mineral has a "fingerprint" Raman spectrum typified by a number of peaks with characteristic frequencies and relative intensities [Wang et al., 1994]. In fact, LRMS has been shown to be useful for identifying major rock-forming minerals, such as silicates, carbonates, sulfates, sulfides, phosphates, oxides, and hydroxides. Additionally, this technique provides direct information to distinguish among polymorphous minerals (e.g., quartz, coesite, stishovite) and to characterize structural distortions due to such processes as shock-induced damage or metamictization.In this paper we first discuss the samples used for LRMS observations, including petrography and chemistry. We next summarize our LRMS measurements of igneous minerals within the host rock, move to analysis of the mineralogy of the varnish from LRMS data for thin sections, and end with a discussion of LRMS observations acquired from hand speci-28,705