S100 - "NWA 17660" Eucrite Polymict HED Achondrite Meteorite Half Stone 154g

Meteorite type & CLASS / OFFICIAL NAME or NUMBER (Meteoritical Bulletin Database): NWA 17660 - HED Achondrite - Eucrite Polymict

FALL/FIND LOCATION: North West Africa

WEIGHT: 153,97g half stone

Size: 7cm x 4cm x 3,9cm

Meteoritical Bulletin Database entry: NWA 17660 Eucrite Polymict

Writeup from Meteoritical Bulletin Database:

Northwest Africa 17660 (NWA 17660)

(Northwest Africa)

Purchased: 2024 Sep

Classification: HED achondrite (Eucrite, polymict)

History: Purchased by Juan Aviles Poblador in September 2024 from a dealer in Erfoud, Morocco.

Petrography: (A. Irving, UWS, and P. Carpenter, WUSL) Complex breccia composed of angular mineral clasts, some fine- to medium-grained lithic clasts with subophitic to intergranular textures, and ~10 vol.% distributed rounded lithic breccia clasts in a fine grained fragmental matrix. The major minerals are exsolved pigeonite, unexsolved pigeonite, calcic plagioclase, subcalcic augite and augite. Minor constituents are diogenitic orthopyroxene (~5 vol.%), silica polymorph, Ilmenite, low-Ti chromite, troilite, fayalite, merrillite, zircon and kamacite. The unusual rounded lithic breccia clasts consist of sparse angular fragments of many of those same mineral phases within an ultra-fine grained opaque to isotropic, microcrystalline to glassy, aluminous matrix (deep sepia brown in thin section), which may represent a quenched melt. Several thin cross-cutting shock melt veinlets are present in the studied thin section.

Geochemistry: Low-Ca pyroxene (Fs64.3Wo2.8; Fs55.5Wo3.3; FeO/MnO = 32-33, N = 2), pigeonite (Fs37.0-40.2Wo6.7-8.0, FeO/MnO = 31-34, N = 2), subcalcic augite (Fs34.3Wo31.9, FeO/MnO = 30), augite (Fs29.4Wo43.0, FeO/MnO = 35), diogenitic orthopyroxene (Fs29.8-31.3Wo4.9-4.4, FeO/MnO = 28-29, N = 2), plagioclase (An79.6-91.8Or1.4-0.2, N = 4), fayalite (Fa75.9-77.8, FeO/MnO = 43-44, N =2), matrix of (?)regolithic breccia clasts with aluminous subcalcic augite bulk composition (Fs43.5Wo29.0, FeO/MnO = 34, Al2O3 13.1 wt.%).

Classification: Eucrite (polymict breccia). This specimen is unusual because of its significant content of eucritic breccia clasts with a microcrystalline to glassy aluminous matrix, which may signify a regolithic component.

Specimens: 27.6 g including one polished thin section at UWB; remainder with Mr. Juan Aviles Poblador.

Observations:

The authenticity of this specimen is guaranteed and certified by me, the Geologist Juan A. Poblador, member of the Global Meteorite Association G0043 and International Meteorite Collectors Association IMCA 5681. 

The fresh cut observed in the specimen is from where a sample was taken for classification and deposit in UWB. And also to make slices of the other half stone.

Scale cube: 1x1cm

Provenance chain: Im the main mass holder - Geologist Juan A. Poblador (Jurassic Dreams - Galactic Dreams Department).

The meteorite would have started its journey to Earth as a result of a massive meteor strike on the Vesta asteroid surface, likely creating huge craters. That initial strike had sufficient force to eject this and other rocks from the surface of the Vesta asteroid at escape velocity, leaving them to float freely in space. Eventually, this mass intersected with the Earth's own orbit where its surface was flash-heated to 2,800 degrees Fahrenheit on entry, then rapidly cooled in the frigid temperatures of Earth's upper atmosphere, before slowing to approximately 200 miles per hour on its final descent. This fall would have lit the Saharan sky up before hurtling down to its site of discovery.