Northwest Africa 12924 (NWA 12924)

Niger

Purchased: January 2018

Classification: Ordinary chondrite (H5, melt breccia)

History: Mendy Ouzillou and Dustin Dickens purchased a single 5.7 kg stone directly from a dealer in Laayoune, Morocco in January 2018.

Petrography: (C. Herd, UAb) Examination of a ~3 × 4.5 cm slice and a ~1 × 2 cm slice (later used to make the thin section) shows dark-gray rounded clasts containing metal and silicates with some microporosity, surrounded by lighter-gray microcrystalline domains which often have vein-like morphology relative to the clasts. Metal grains in the clasts are mostly <0.5 mm, but locally up to 8 mm in longest dimension. At thin section scale, the clasts consist of poorly delineated chondrules, metal and sulfides in a typical equilibrated ordinary chondrite texture. Microcrystalline domains are glassy in places, and contain fragments of the larger clasts; these are likely shock melt veins. Other shock effects include strong mosaicism in olivine.

Geochemistry: (C. Herd and L. Tunney, UAb) Data obtained by EMP examination of carbon-coated thin section, grey clasts only: Olivine Fa_18.8±0.4 (n=8); Low-Ca Pyroxene Fs_16.3±0.2, Wo_1.3±0.2 (n=5); Feldspar Or_2.5Ab₈₁ (n=1).

Classification: Ordinary chondrite, H5-melt breccia. Likely paired with Tassedet 004.

Specimens: Type specimen of 20.1 g, including one thin section, at UAb. Mendy Ouzillou 2.85 kg, Dustin Dickens 2.85 kg.