Northwest Africa 11607 (NWA 11607)

Northwest Africa

Purchased: 2017

Classification: Carbonaceous chondrite (CK3-6)

History: The meteorite was bought from a meteorite dealer in Morocco.

Physical characteristics: Dark grayish to black individual partly covered with fusion crust.

Petrography: The meteorite is a chondritic breccia composed of angular to subrounded type 3-6 clasts set into a more fine-grained clastic matrix. The different clasts are up to 2 cm in size and vary in color from light greenish to almost black. Matrix dominates over chondrules which are on average about 1.2 mm in diameter. Ferroan, Ni-rich olivine is the most abundant mineral in all lithologies. While highly unequilibrated in type 3 clasts and matrix it is equilibrated at Fa_29.6 in type 5 and 6 lithologies. One type 6 fragment with more Fe-rich olivine (Fa₃₅) has been encountered. Less abundant are Ca-pyroxene, low-Ca pyroxene, and intermediate feldspar. Feldspar is up to 200 µm in size in type 6 lithologies and often intergrown with Ca-pyroxene. The meteorite containes abundant Cr-bearing magnetite and some FeNi-sulfides.

Geochemistry: Type 3 lithology: olivine: Fa_22.4±12.7 (Fa_1.7-34.0, NiO=0.3±0.2; FeO/MnO=103±31, n=32); low-Ca pyroxene: Fs_16.3±8.0Wo_0.9±0.9 (Fs_2.9-27.7Wo_0.5-4.1, n = 15), Ca-pyroxene: Fs_10.9±4.8Wo_33.8±6.5 (Fs_2.4-17.6Wo_23.1-45.1, n = 9); type 6 lithology: olivine: Fa_29.6±0.6, NiO=0.4±0.1, FeO/MnO= 105±9, n=42; low-Ca pyroxene: Fs_26.9±0.8Wo_1.1±0.4, n=9, Ca-pyroxene: Fs_11.6±2.6Wo_39.3±6.6, n=13; Fe-rich fragment: olivine: Fa_35.0±0.3, NiO=0.4±0.1, FeO/MnO= 143±13, n=38; Ca-pyroxene: Fs_12.6±1.3Wo_46.5±1.6, n=29; plagioclase: An_78.8Ab_20.9Or_0.3, n=3; andesitic feldpar: An_35.0Ab_64.3Or_0.7, n=3; Cr₂O₃ in magnetite is about 4.9 wt%.