Petrology of the Unbrecciated Eucrite, Cumulus Hills 04049

Introduction: Eucrite meteorites represent earlyformed (~4.557-4.565 Ga) crustal basalts and basaltic to gabbroic cumulates from the howardite-eucritediogenite (HED) parent body or bodies (e.g., [1]). The HED are commonly thought to originate from the asteroid Vesta (e.g., [2-3]), although O-isotopes for eucrites [4] and diogenites [5] indicate more than one parent body. Approximately 85% of eucrites in the terrestrial collections are polymict to monomict breccias, with the remainder of eucrites being unbrecciated. The unbrecciated eucrites are important for understanding lithological diversity on their parent body(ies), which is especially relevant with the ongoing DAWN mission to Vesta [1]. Unbrecciated eucrites are also important for understanding early planet differentiation mechanisms, where unbrecciated eucrites may be free from the influence of postcrystallization impact additions. Here we present the petrology and mineral chemistry of eucrite Cumulus Hills (CMS) 04049. Methods: Petrography and mapping of the section CMS 04049, 27 was performed using a petrographic microscope. Regions of interest were further imaged and quantitative major mineral compositions were analyzed using a Cameca SX-100 electron microprobe at the University of Tennessee. Mineral chemistry: CMS 04049 is a monomict unbrecciated eucrite with a predominantly sub-ophitic texture (Figure 1) with 35:65 plagioclase to pyroxene, and lesser amounts of silica, ilmenite, chromite and troilite with minor zircon and olivine, broadly consistent with previous observations [6-7].