Asteroid 3628 Božněmcová: Covered with angrite-like basalts?

Abstract

A detailed analysis of the reflectance spectrum of asteroid 3628 Božněmcová, previously identified as a possible ordinary chondrite parent body, indicates that its surface consists of an assemblage dominated by clinopyroxene and plagioclase feldspar. The clinopyroxene is Fe2+-bearing (likely in the range Fs~10-20), with >90% of the Fe2+ being present in the M1 crystallographic site (spectral type A). The clinopyroxene:plagioclase feldspar ratio is between ~2 and 3 (~55-75% clinopyroxene, ~20-33% plagioclase feldspar). If olivine is present, the clinopyroxene:olivine ratio is >~3 (<20% olivine). The derived mineralogy of Božněmcov is most similar, but not identical, to the known angrite meteorites. The data suggest that Božněmcov formed by melting and differentiation of an oxidized chondritic precursor and probably represents an unsampled angrite-like body.