Northwest Africa 15431 (NWA 15431)

(Northwest Africa)

Purchased: Mar 2020

Classification: Lunar meteorite (frag. breccia)

History: Meteorite was purchased by Mr. Jasper Spencer from a Moroccan dealer (Nor Eddine Azelmat) in March 2020 via e-mail. Mr. Spencer sent a 7.9 g end piece to Cascadia for classification.

Physical characteristics: Physical Characteristics: The exterior of the sample is covered with a desert varnish; no evidence of a fusion crust was visible on the end piece received by Cascadia. The cut face shows sub-angular to sub-rounded clasts in a variety of colors, including white, cream, light brown, reddish-brown to black, set in a dark brownish-gray matrix.

Petrography: (M. Hutson and A. Ruzicka, Cascadia): Sample is a breccia comprised of large (up to 3 mm in length) sub-angular to sub-rounded lithic clasts set in a matrix of finer (< 250 µm) angular clastic material. The larger clasts contain abundant glass, while the matrix contains crystalline anorthitic feldspar. Accessory phases include ilmenite, silica polymorph, armalcolite, troilite, FeNi-metal, and Ca-phosphate grains observed in x-ray maps but too small to analyze.

Geochemistry: (M. Hutson and A. Ruzicka, Cascadia): Plagioclase feldspar: Ab_4.2±2.0Or_0.6±0.4An_95.2±2.1, N=33; Glass (in large clasts): Ab_4.5±5.6Or_1.2±1.4An_94.3±6.0, N=21; Olivine: Fa_40.1±8.9, Fe/Mn=87.2±5.0, N=9; Low-Ca pyroxene: Fs_23.5±8.4Wo_3.6±0.6, Fe/Mn=55.0±8.6, N=21; Pigeonite: Fs_24.8±7.7Wo_10.0±3.9, N=13; Augite: Fs_21.8±20.6Wo_40.7±9.0, N=19.

Classification: Lunar (frag. breccia). This meteorite is best described as a lunar feldspathic fragmental breccia based on texture and chemistry.

Specimens: Cascadia holds 6.9 g in two pieces, as well as a polished thin section and material in an epoxy butt; Mr. Jasper Spencer holds the main mass.