Using petrology and mineralogy to understand the surface of Vesta: a collection of fine-grained eucrites

Abstract

Fine-grained eucrites in howardites may help us understand the geologic history of the asteroid 4Vesta, as they represent the crustal material. Recent work by Mayne et al. (2010) suggests that fine-grained eucrites are not common in the eucrite collection alone and that eucrite clasts in howardites may show a greater variety. After looking at the entire US Antarctic and non-Antarctic howardite collection in the Smithsonian's Department of Mineral Sciences, five howardites were found to have eight fine-grained eucrite clasts within them, out of over 200 howardite samples. SEM mineral maps were used to identify textures and initial geochemistry, and electron microprobe data were obtained for detailed chemical analysis. Results show that even within a small group of fine-grained eucrites, the clasts have a great textural and compositional variety. This implies that geologic events on Vesta's crust were small-scale, localized and very complex.