Angrites

Rare samples of an early body

The exact source has not been definitively identified. Chemistry and isotopes nevertheless indicate a differentiated body in the inner Solar System.

Mineralogy and exceptional age

Angrites are basaltic achondrites with unusual chemistry. Calcium-rich pyroxenes, olivine and anorthite are typical, and many are depleted in volatile elements. Their mineral assemblage clearly differs from HED basalts and Martian meteorites.

Some angrites crystallised only a few million years after the first Solar System solids. Their precise radiometric ages are therefore key markers for early differentiation, short-lived isotope decay and planetary chronology.

Rapidly quenched or slowly cooled

Some angrites are fine-grained and vesicular, probably quenched rapidly in near-surface lava. Others are coarser and cooled more slowly at depth. The group therefore preserves several levels of a magmatically active small planet.

The specific parent body is unknown. Chemical and isotopic evidence indicates a distinct differentiated world in the inner Solar System, but no direct assignment to a currently observed asteroid is secure.