Northwest Africa 5000

Morocco

Find: July 2007

Achondrite (lunar, feldspathic breccia)

History: Found in July 2007 in southern Morocco and provided to Adam Hupé in October 2007.

Physical characteristics: A single, large cuboidal stone (11.528 kg) with approximate dimensions 27 cm × 24 cm × 20 cm. One side (which appears to have been embedded downward in light brown mud) has preserved regmaglypts and is partially covered by translucent, pale greenish fusion crust with fine contraction cracks. Abundant large beige to white, coarse-grained clasts up to 8 cm across (some of which have been eroded out on exterior surfaces of the stone, likely by eolian sand blasting) and sparse black, vitreous clasts up to 2 cm across (containing irregular small white inclusions) are set in a dark gray to black, partially glassy breccia matrix. One partially eroded clast exposed on an exterior surface contains both the coarse grained beige lithology and the more resistant black, vitreous lithology in sharp contact.

Petrography: (A. Irving and S. Kuehner, UWS) Almost monomict fragmental breccia dominated by Mg-suite olivine gabbro clasts consisting predominantly of coarse-grained (0.5-2 mm) calcic plagioclase, pigeonite (some with fine exsolution lamellae), and olivine with accessory merrillite, Mg-bearing ilmenite, Ti-bearing chromite, baddeleyite, rare zirconolite, silica polymorph, K-feldspar, kamacite, and troilite. Some gabbro clasts have shock injection veins composed mostly of glass containing myriad fine troilite blebs and engulfed mineral fragments. Black, vitreous impact melt clasts consist of sporadic, small angular fragments (apparently surviving relics) of gabbro and related mineral phases in a very fine grained, non-vesicular, ophitic-textured matrix of pigeonite laths (up to 20 microns long × 2 microns wide) and interstitial plagioclase with tiny spherical grains of kamacite, irregular grains of schreibersite and rare troilite.

Geochemistry: Gabbro clasts: plagioclase (An_96.1-98.0Or_<0.1), pigeonite (Fs_32.0-64.5Wo_6.7-13.1; FeO/MnO = 51.1-62.0), olivine in different clasts range from Fa_23.9-24.2, Fa_40.4 to Fa_58.8 (with FeO/MnO = 81-100), chromite [(Cr/(Cr + Al) = 0.737, Mg/(Mg + Fe) = 0.231, TiO₂ = 5.9 wt%], ilmenite (4.1 wt% MgO). Bulk composition: (R. Korotev, WUSL) INAA of 6 subsamples gave mean values of 5.3 wt% FeO and 0.4 ppm Th.

Classification: Achondrite (lunar, feldspathic breccia). Specimens: A total of 40.2 g of sample, two polished mounts and one large polished thin section are on deposit at UWS. AHupé hold the main mass.

Submitted by: A. Irving, UWS.