Northwest Africa 13950 (NWA 13950)

(Northwest Africa)

Purchased: 2021 Jan

Classification: Carbonaceous chondrite (CR2)

History: The meteorite was purchased from a meteorite dealer in Nouadhibou, Mauritania, in late January, 2021.

Physical characteristics: Seventeen brownish fragments without fusion crust.

Petrography: The meteorite is composed of abundant large and mostly porphyritic type I chondrules (apparent mean diameter about 700 μm) set into a fine-grained iron-rich matrix. Few type II chondrules but no CAIs have been found in the two sections studied. Type I chondrules are often metal-decorated and contain abundant metal blebs. Type II chondrules contain sulfides and very rare metal. The matrix contains framboids of ~1 μm-sized round to euhedral magnetite grains and low analytical totals suggest presence of hydrous mineral phases.

Geochemistry: olivine in type I chondrules: Fa_2.5±1.4 (Fa_1.1-5.4, Cr₂O₃: 0.65±0.08 wt%, n=20; low-Ca pyroxene: Fs_2.3±1.3Wo_1.3±0.7 (Fs_1.2-4.9Wo_0.8-3.2, n=13); Fe-rich olivine grains: Fa_37.8±6.1 (Fa_32.0-49.9, n=6). Matrix analyses yield an average total of 87.8±0.7 wt% (5 μm defocused beam, n=5) suggesting the presence of hydrous minerals.