Northwest Africa 10881 (NWA 10881)

(Northwest Africa)

Purchased: 2015

Classification: Carbonaceous chondrite (CO3.0)

History: Purchased by Mohammed Hmani in 2015.

Physical characteristics: Single stone. Weathered fusion crust exterior. A saw cut reveals many very small chondrules and a few small CAIs set in a dark brown matrix.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows numerous chondrules, many fragmental or irregular, most in the size range 50-200 μm. Scattered matrix olivines and CAIs were observed throughout. Fine grained matrix makes up approximately 50% of this meteorite. The metal abundance is low. The CAIs are small and scattered.

Geochemistry: (C. Agee and M. Spilde, UNM) All olivine Fa_11.0±15.3, n=30; coarse ferroan olivine Fa_28.7±11.6, Fe/Mn=119±66, Cr₂O₃=0.38±0.08 (wt%), n=11; enstatite Fs_2.4±1.9Wo_1.3±0.7, n=8; diopside Fs_3.6±3.8Wo_41.4±6.0, n=3; (K. Ziegler, UNM) Oxygen isotope mean values of analyses on 3 acid-washed fragments of bulk sample, 1.2, 1.5, 1.5 mg, gave δ¹⁷O= -7.053, -4.062, -4.822, δ¹⁸O= -2.269, 1.814, -0.062, Δ¹⁷O= -5.855, -5.020, -4.789, (linearized, all permil). One of the fragments had O-isotopes near the CO field, the other two were more in the CV/CK field.

Classification: Carbonaceous chondrite (CO3.0), type 3.0 based on mean value and sigma of Cr₂O₃ in ferroan olivine (Grossman and Brearley, 2005), the values are similar to ALHA77307.

Specimens: 29.8 g including a probe mount on deposit at UNM, Mohammed Hmani holds the main mass.