Recent discoveries of ungrouped achondrites reveal that early Solar System crusts include evolved lithologies, demonstrating that differentiated bodies were not simply restricted to mafic compositions. These samples represent some of the oldest known differentiated materials, providing critical constraints on the processes that governed planetary formation and evolution. Despite their significance, silica-rich meteorites and their asteroidal counterparts remain exceedingly rare, as their parent bodies are thought to have been catastrophically disrupted and are largely absent from the present-day Solar System. Here we report the spectroscopic characterization of eight silica-rich, ungrouped achondrites, representing at least five distinct parent bodies defined by chemical and oxygen isotopic compositions, and evaluate their potential asteroidal sources. Asteroid (10537) 1991 RY 16 remains the best candidate for a silica-rich surface lithology and is potentially linked to Northwest Africa (NWA) 11,575.
Rider-Stokes et al. (Mon,) studied this question.