diogenite

Diogenite is a group of achondritic stony meteorites and one of the three principal subgroups of the HED meteorites, alongside eucrites and howardites. They are characterized by a predominantly orthopyroxene-rich mineral assemblage and a coarse-grained to granular texture, with only minor amounts of other minerals.

The mineralogy of diogenites is dominated by orthopyroxene, with accessory components such as plagioclase, olivine, chromium-rich spinel, and rare phosphates or sulfides. The rocks are commonly described as orthopyroxenites, and their textures suggest crystallization under relatively slow cooling in a magma chamber or cumulate differentiation environment. Composition and texture variants within diogenites reflect different depths and cooling histories within the parent body.

Diogenites are thought to originate from the crust or upper mantle of asteroid 4 Vesta, forming from basaltic magmas that crystallized early in the solar system. They represent material that is related to, but distinct from, eucrites (basaltic crustal rocks) and are related to howardites, which are breccias incorporating eucrite and diogenite fragments. Together, the HED suite provides insights into planetary differentiation processes on Vesta and helps inform models of crust-mantle evolution on differentiated asteroids.

In the meteorite record, diogenites are less common than eucrites but are highly valued for their pristine orthopyroxene-rich composition, which preserves information about early magmatic processes. Their study, along with eucrites and howardites, contributes to understanding the geology of Vesta and the broader history of the early solar system.