Nakhlite

One of the Martian SNC meteorites, nakhlites are basaltic cumulate clinopyroxenite rocks, and most all are comprised mainly of sub-calcic augite with approximately 10% Fe-rich olivine (giving the augite a green color) that are set in a very fine-grained matrix (mesostasis) comprised of plagioclase, K-feldspar, clinopyroxene, Fe-Ti oxide (Ti-magnetite), sulfide, and phosphate. Differences among the chemical compositions of the nakhlites can be ascribed mostly to different proportions of augite, olivine, and mesostasis1.

Nakhlites formed as thick basic/ultrabasic lava flows or shallow intrusions of basaltic magma on Mars and have a relatively recent crystallization age of 1.3 Ga. Based on the age of hydrated minerals, including clays and carbonates, they are thought to have been exposed to water less then 670 Ma. Analysis of their known formation depths coupled with observed hydrothermal veining continues to provide important information about the interaction between water and the Martian crust. Research suggests that all nakhlites were ejected from Mars during a common impact event 10 to 12 Ma2.