HED Meteorites

HED meteorites are a group of achondrite meteorites believed to originate from the large differentiated asteroid 4 Vesta, one of the biggest bodies in the asteroid belt. These meteorites were ejected into space by massive impact events, most notably those that created Vesta’s massive south polar impact basins. With Vesta’s relatively low gravity compared to planets, debris from these collisions was able to escape into solar orbit, where some fragments eventually crossed paths with Earth. Upon entering our atmosphere, a small number survive as meteorites, offering a direct link to one of the earliest formed bodies in the solar system. While more common than Martian or lunar meteorites, HED meteorites remain highly significant to both scientists and collectors.

The term 'HED' refers to the three main subtypes: Howardites, Eucrites, and Diogenites. Eucrites are basaltic rocks formed from ancient lava flows on Vesta’s surface, while Diogenites are coarser-grained rocks that crystallized deeper within the asteroid’s crust. Howardites are brecciated mixtures of both Eucrites and Diogenites, created by repeated impact gardening on Vesta’s surface. Like other achondrites, HED meteorites lack chondrules and instead display igneous textures, reflecting a history of melting and differentiation similar to that of larger planetary bodies. Their mineral composition, dominated by pyroxene and plagioclase, closely matches data collected by NASA’s Dawn spacecraft, confirming their Vestan origin.

Studying HED meteorites provides valuable insight into the processes of planetary formation and differentiation in the early solar system. Because Vesta is considered a protoplanet (a building block of terrestrial planets) these meteorites preserve a record of volcanic activity, crust formation, and impact history dating back over 4.5 billion years. Their diversity reflects different depths and regions within Vesta, giving researchers a layered understanding of its internal structure. For collectors, HED meteorites represent an accessible yet scientifically rich category, offering a tangible piece of a primordial world that bridges the gap between small asteroids and fully formed planets.