Mineralogical study of Itokawa asteroidal particles: Reconfirmation of their similarities to equilibrated LL chondrites

Abstract

We performed mineralogical study on 7 Itokawa particles returned by the Hayabusa spacecraft. The analyzed particles constitute of olivine and plagioclase with minor shock metamorphism (shock stage: S2). Olivine is Fo_70-73, consistent with the cell dimensions obtained by SR-XRD and close to LL chondrites. Plagioclase is An_13-10Or_5-7 and its equilibration temperature is ~800^oC. Fe SR-XANES of plagioclase suggests high fO2 and affinities with LL chondrites. Their petrologic type is ≥4 based upon plagioclase sizes and homogeneous olivine compositions. Thus, this study demonstrates that analyzed particles could be equilibrated LL chondrites with minor shock metamorphism, reconfirming the preliminary examination study.