Northwest Africa 16746 (NWA 16746)

Morocco

Purchased: 2023 Oct 27

Classification: Ordinary chondrite (LL7)

History: (Ziyao Wang, WangZ) Purchased by Lu Dongdong and Wang Taiguang from a Moroccan dealer at the mineral show on Oct. 27, 2023.

Physical characteristics: (Ziyao Wang, WangZ) greenish-brown stone of 467 g, without fusion crust.

Petrography: (R. Bartoschewitz, Bart) The thin section shows a strong recrystallized fine grained (~0.1 mm) cataclastic breccia, partly with interstitial plagioclase network, plagioclase patches up to 300 µm, single pyroxen fragments up to 6 mm, and rare relict chondrules. Ca-rich augite with rare exsolution lamellae. Chromite shows sub-rounded and bulby grains up to 150 µm; metal occurs as bulby intergranular aggregates up to 100 µm and tiny silicate impregnation, often adjacent to troilite; troilite forms subrounded grains and intergranular vermicular veins. One ilmenite grain was found.

Geochemistry: (R. Bartoschewitz, Bart, and P. Appel, Kiel) Olivine Fa_30.2±0.3 (n=14); low Ca pyroxene Fs_24.4±0.8Wo_2.2±0.3 (n=13); augite En_46-59Fs₁₀Wo₄₄ (n=5); feldspar An_10-11Or_3-4 (n=6); chromite CRAL=85-87, FFM=91-92 (n=3). Taenite/tetrataenite Ni=46.3-50.0, Co=1.9-2.2 (n=6); troilite Ni<0.16 (n=11) (wt%). Magnetic susceptibility (R. Bartoschewitz, Bart) log χ (× 10^-9 m³/kg) = 3.34

Classification: Ordinary chondrite (LL7, S2, W1-2). Type 7 due to plagioclase network and large plagioclase patches, Wo_>2, and Ca-rich augite with exsolution lamellae.

Specimens: 13.2 g on deposit at UGött plus 8.4 g on deposit at IfP, main mass with Lu Dongdong and Wang Taiguang, 56 g and polished thin section with Bart