NWA 17660 — HED, an Unusual Eucrite Specimen from Asteroid 4 Vesta - 153 g

A remarkable piece of the asteroid 4 Vesta in your hands.

Offered here is a beautiful specimen of Northwest Africa 17660 (NWA 17660), an officially classified HED achondrite — Eucrite, polymict breccia.

NWA 17660 is a particularly interesting eucrite because it is far more complex than a typical polymict eucrite. According to the official classification from the Meteoritical Bulletin, this meteorite is a complex breccia containing angular mineral fragments, fine- to medium-grained lithic clasts and approximately 10 vol.% rounded lithic breccia clasts dispersed within a fine-grained fragmental matrix.

The mineral assemblage is dominated by pigeonite and calcic plagioclase, accompanied by subcalcic augite and augite. Minor phases include diogenitic orthopyroxene, silica, ilmenite, chromite, troilite, fayalite, merrillite, zircon and even kamacite.

What makes NWA 17660 especially fascinating, however, are its unusual rounded breccia clasts. These contain fragments of several of the same minerals enclosed within an ultra-fine-grained, opaque to isotropic, microcrystalline-to-glassy aluminous matrix. The classification team notes that this unusual material may represent quenched impact melt and could signify a regolithic component. Several thin shock-melt veinlets also cross-cut the studied material — providing a remarkable record of the violent impact history experienced by this rock on its parent body.

Like other eucrites, NWA 17660 ultimately comes from the differentiated asteroid 4 Vesta, the parent body of the HED meteorites and the second largest asteroid in the Asteroid Belt. This specimen therefore represents a piece of an ancient basaltic crust that was excavated, fragmented and repeatedly processed by impacts before eventually being liberated from Vesta and making its way to Earth.

Official classification

Northwest Africa 17660 (NWA 17660)
Classification: HED achondrite — Eucrite, polymict breccia
Status: Official
Year found: 2024
Total approved mass: 544 g
Weathering: Low
Shock: Low–high
Classification approved: 1 June 2025
Classifiers: A. Irving, UWS & P. Carpenter, WUSL
Type specimen: 27.6 g, including one polished thin section at the University of Washington Burke Museum

NWA 17660 is therefore not simply another piece of eucrite. Its complex mixture of eucritic lithologies, diogenitic material, unusual aluminous glassy/microcrystalline clasts and shock-melt veins preserves evidence of the violent impact processes that shaped the crust of Vesta.

A beautiful and scientifically fascinating addition to any HED, Vesta, differentiated-asteroid or achondrite collection.

I am a member of the Meteoritical Society (#7743) and Global Meteorite Association (#G0129) have been collecting meteorites for over 16 years.