Northwest Africa 11354 (NWA 11354)

Morocco

Purchased: Feb. 2017

Classification: Enstatite achondrite (ungrouped)

History: Purchased by Ke Zuokai in Feb. 2017 from a Moroccan dealer.

Physical characteristics: The meteorite is covered by a dark brown fusion crust.

Petrography: The meteorite is composed of medium-grained (~0.1-0.5 mm) silicates, metal and sulfide. Enstatite is the dominant silicate phase. Other silicates are olivine, albitic plagioclase and fine-grained diopside (4-20 μm). No chondrules or clasts are observed. Some regions of the thin section exhibite triple junctions. Metal and sulfide include kamacite, tanite, troilite, alabandite, daubreelite and schreibersite. Daubreelite often presents as lamellae within troilite.

Geochemistry: Enstatite Fs_0.7-2.0Wo_0.7-1.7 (n=19), Fe/Mn (cation ratio)=8.0±3.9; minor fine-grained Ca-rich pyroxene Fs_43.1-47.2Wo_43.1-47.2 (n=9), Fe/Mn (cation ratio)=16.6±10.8; plagioclase Ab_71.5-83.6Or_0.01-3.4 (n=9); olivine grains are almost pure fosterite Fo_99.3-100 (n=18), Fe/Mn (cation ratio)=3.1±1.6. This meteorite lacks Si content in metal. Kamacite (wt%) Fe 92.49, Ni 5.99, Co 0.51, P 0.05. Taenite (wt%) Fe 75.71, Ni 23.55, Co 0.31. Troilite (wt%) Fe 63.11, S 36.07, Co 0.13, Ti 0.18, Cr 0.29, V 0.06. Daubreelite (wt%) Fe 19.69, Cr 36.44, S 44.28, Ni 0.07, Ti 0.01, P 0.04, Co 0.05. Sulfide is low in Si (below 0.01 wt%).

Classification: Enstatite achondrite ungrouped. The meteorite is chemically similar to equilibrated EL chondrites. However, it is distinguished from EL6 chondrite by the lack of chondrules and presence of olivine. Moreover, this meteorite has low Si content in metal (below detection limit) and low Ti content in troilite (0.16±0.02 wt%), similar to those in NWA 10519 (Enst achon-ung).