Northwest Africa 12379 (NWA 12379)

Morocco

Find: 2017 Aug to 2018 Sep

Classification: Ungrouped chondrite

History: Found between August 2017 and September 2018 close to the border between Morocco and Algeria

Physical characteristics: (Luc Labenne) Five individuals covered by typical NWA iron meteorite desert patina and very well preserved inside.

Petrography: (C. A. Jansen, Frank E. Brenker, J. Zipfel, Senck, A. N. Krot, UH) The meteorite is very metal-rich consisting of ~70 vol% Fe,Ni, ~25-30 vol% silicates, <5 vol% troilite and is completely free of matrix. Minor quantities of Fe-oxides, probably of terrestrial origin, are present. The silicate portion is dominated by abundant, well-rounded chondrules up to 1.2 mm, mostly POP, PO and PP types. Many chondrules are fragmented. Metal phases are predominantly kamacite; taenite and tetrataenite are rarer. Accessory troilite occurs as coarse isolated grains, occasionally associated with tetrataenite. Merrillite, chlorapatite and chromite are found inside metal grains and in peripheral parts of some chondrules.

Geochemistry: Mineral compositions and geochemistry: Porphyritic chondrules: olivine Fa_25.3±3 (Fa_18.1-28.5, median Fa_26.5, Cr₂O₃=0.03±0.02 wt%; FeO/MnO=53.6±5.9, N=36); low-Ca pyroxene Fs_14.7±3.7Wo_1.4±1.3 (Fs_3.2-18.7Wo_0.2-4.5, median Fs_15.8Wo_0.8, N=19). Isolated low-Ca pyroxene grains enclosed by metal and low-Ca pyroxene phenocrysts in some chondrules are replaced to various ° by Fe-rich olivine (Fa_27.3±0.6; FeO/MnO=53.8±4.1; N=13). This data was acquired by EPMA. Oxygen isotopes: (A. Pack, UGött) δ¹⁷O=3.69‰, δ¹⁸O=5.14‰, Δ¹⁷O=+0.96‰.

Classification: Chondrite (ungrouped). Based on the chemical composition of the silicate fraction as well as the common presence of chromite and phosphates in combination with oxygen isotopes the sample shows affinity to ordinary chondrites. The olivine Fa content is not homogenized throughout the sample and the standard deviation is within the range of type 3 ordinary chondrites. The high metal content, however, is inconsistent with ordinary chondrite. Based on its petrographic and geochemical properties and oxygen isotope data, this meteorite is probably paired with NWA 12273. Luc Labenne for providing important information and a second sample for oxygen isotope analyses.