Spectral reflectance properties of ureilites

Abstract- The 0.35-2.6 μm reflectance spectra of 18 ureilites have been examined in order to improve our understanding of the spectral reflectance properties of this meteorite class. Across this spectral range, ureilite spectra are characterized by a steep rise in reflectance over the 0.3 to approximately 0.7 μm range, low overall reflectance (<25%) and weak mafic iron silicate absorption bands in the 1 and 2 μm region. The weakness of these bands and the low reflectance are attributed to the presence of dispersed graphite and related carbonaceous phases, metal, and possibly shock. Wavelength positions of the mafic silicate absorption bands span a range of values, but are consistent with the presence of pyroxene and olivine. Ureilite spectra generally exhibit blue slopes across the 0.7-2.6 μm interval and exhibit many overall similarities to some carbonaceous chondrites. The weak features and spectral diversity of ureilites make reflectance spectroscopy-based identification of a ureilite parent body challenging. As terrestrial alteration of ureilites is prevalent, spectral studies of falls are most useful for determining the spectral properties of likely parent bodies.