Northwest Africa 12386 (NWA 12386)

(Northwest Africa)

Purchased: 2018 Mar

Classification: Ordinary chondrite (L5)

History: A meteorite, broken into two pieces, was purchased at Ouarzazate, Morocco, in May 2018. The smaller one, 289.1 g, has a broken surface, with the remaining surface covered with fusion crust. The cut surface of the smaller meteorite indicates the sample has an achondritic texture. The larger stone, 1192.5 g, is composed of two parts: the chondritic main body and an igneous clast. The larger stone also has a broken surface, with other surfaces covered by fusion crust.

Physical characteristics: The meteorite is composed of two lithologies: an ordinary chondrite and an igneous clast.

Petrography: The igneous clast is composed mainly of olivine (70 vol%), feldspar (15 vol%), high-Ca pyroxene, and minor minerals (including phospate, troilite and Fe-Ni metal). Almost no low-Ca pyroxene was found. The abundance of Fe-Ni metal is about 1 vol%. Olivine occurs as phenocrysts, with a particle size of 200-300 μm. The feldspar occurs as interstitial grains filled with skeletal crystals of high-Ca pyroxene.

Geochemistry: For the L5 ordinary lithology: Olivine Fa_23.1±2.7 (N=23), CaO 0.04±0.03 wt% MnO 0.42±0.05 wt%; low-Ca pyroxene Fs_21.7±2.7Wo_2.1±0.2 (N=6). For the igneous clast: Olivine Fa_22.1±3.3 N=34), CaO 0.07±0.06 wt% MnO 0.41±0.05 wt%. Oxygen isotopes (Huiming Bao, LSU): Analyses of three acid-washed whole rock of the clast lithology by CO₂ laser fluorination: δ¹⁸O = 4.803, 4.825, 4.795; δ¹⁷O = 3.568, 3.552, 3.543; Δ¹⁷O = 1.020, 0.992, 0.999 (all permil).