Formation of NWA 7325 Ungrouped Achondrite as Inferred from Its Mineralogy and Noble Gas Compositions.

Abstract

The study of ungrouped achondrites is important to understand the degree of asteroidal diversity and igneous differentiation in the early solar system. NWA 7325 is such an ungrouped achondrite and has drawn attention as the first meteorite sample possibly from the planet Mercury. In this study, we analyzed NWA 7325 using FEG-SEM with EDS and EPMA, and subseqently measured its noble gases. We suggest that the parent body of NWA 7325 has experienced a break-up event to partially melt and quench the mantle rock by shock in the early solar system while ¹²⁹I was still present.