HED meteorites
The related family of howardites, eucrites and diogenites, thought to come from the asteroid Vesta.
The HED meteorites are a clan of three achondrite groups that share oxygen isotopes and seem to come from one differentiated parent body. Eucrites are basaltic lavas and gabbros from the crust, diogenites are pyroxene-rich rocks from deeper down, and howardites are rubbly breccias that mix the two. Together they make the largest family of achondrites and offer a cross-section through an entire small world.
The likely source is the asteroid 4 Vesta, about 525 kilometres across. In the 1970s its reflected light was found to match basaltic meteorites in the laboratory. NASA's Dawn spacecraft, which orbited Vesta in 2011–2012, mapped pyroxene-rich terrain and the huge Rheasilvia impact basin near the south pole, a likely source of the small "Vestoid" asteroids that may deliver HEDs to Earth. Classic examples include the eucrite Juvinas (France, 1821), the diogenite Tatahouine (Tunisia, 1931) and the howardite Kapoeta (South Sudan, 1942).
HEDs often have a shiny black fusion crust that contrasts with a pale grey interior. Many are breccias of angular fragments. Feldspar-bearing eucrites look like fine volcanic rock, while diogenites show greenish-yellow pyroxene crystals.
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