File:NWA7831 1,301g slice.jpg

Vesta is the largest and brightest asteroid in the asteroid belt and the second largest body overall (after the dwarf planet Ceres), with an average diameter of about 525 km (326 miles). That is pretty close to the size of the State of Colorado.

A couple of billion years ago two massive impacts ejected part of Vesta’s mass and some of that material landed here on Earth as HED (howardite, eucrite, and diogenite) meteorites. It’s astonishing to consider that when you look at photographs of Vesta, or eve through a powerful telescope, the actual craters from which the HED meteorites were blasted out can easily be seen, such as Rheasilvia which is over 300 miles wide.

Diogenites: “Vast underground chambers of magma churned and roiled, eventually cooling to the point at which orthopyroxene crystals froze out of the liquid rock. Insulated by kilometers of overlying rock and magma, they cooled slowly, growing into enormous sizes before settling downwards into vast piles of large crystals at the base of the underground caverns.” (<a href="https://www.flickr.com/photos/jurvetson/51000316812/">Meteorite</a>, p.102)

From the Meteorite Bulletin for <a href="https://www.lpi.usra.edu/meteor/metbull.php?code=57282" rel="noreferrer nofollow">NWA 7831</a>:

History: Found buried in the ground near Chouichiyat in the Western Sahara on March 3, 2013, and excavated by a team of local people.

Physical characteristics: composed of translucent yellow-green crystals of orthopyroxene with pale orange weathering products along numerous fractures. Much of the material disintegrated into fragments upon excavation.