Northwest Africa 8649 (NWA 8649)

(Northwest Africa)

Purchased: 2014

Classification: Ordinary chondrite (LL3.05)

History: Purchased by Aziz Habibi in Morocco, 2014.

Physical characteristics: A single stone with fusion crust, weathered exterior. Saw cut reveals many densely packed chondrules of variable size; iron-oxidation present.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount and polished deposit sample shows numerous unequilibrated chondrules, apparent mean diameter 602±386 μm (n=105), many with porphyritic, igneously zoned olivines and pyroxenes, most with glass or mesostasis. Abundant fine-grained matrix throughout.

Geochemistry: (C. Agee, N. Muttik, UNM) All chondrule olivine Fa_16.9±8.7 (Fa_0.8-39.4, n=92); ferroan olivine Fa_17.5±8.4, Fe/Mn=46±17, Cr₂O₃=0.41±0.15 wt%, n=88; low-Ca pyroxene Fs_13.3±9.2Wo_1.1±1.1, Fe/Mn=28±19, n=47; pigeonite Fs_17.3±5.4Wo_8.9±2.8, Fe/Mn=29±19, n=3; high-Ca pyroxene Fs_17.8±15.1Wo_28.8±6.0, Fe/Mn=13±11, n=5. Oxygen isotopes (K. Ziegler, UNM) 12 acid-washed samples of 1.5, 2.1, 1.6, 2.1, 1.8, 1.4, 1.3, 1.3, 2.3, 1.6, 2.1, and 3.5 mg gave δ¹⁷O = 2.875, 3.300, 3.713, 2.938, 2.543, 2.623, 3.249, 2.807, 3.217, 3.302, 3.563, 3.518, δ¹⁸O = 4.896, 5.022, 5.094, 4.609, 4.203, 4.464, 4.779, 4.639, 4.669, 4.585, 5.659, 5.766, Δ¹⁷O = 0.290, 0.648, 1.023, 0.504, 0.324, 0.266, 0.726, 0.358, 0.752, 0.881, 0.575, 0.474 (linearized, all permil).

Classification: Ordinary chondrite (LL3.05), type 3.05 based on ferroan olivine mean Cr₂O₃ content and sigma from Grossman and Brearley (2005), similar values to MET 00526. Oxygen isotopes appear to be relatively heterogeneous and fall within the same range of δ¹⁷O and δ¹⁸O as NWA 7731 (Ziegler et al., LPSC, 2014). Weathering grade (W3). Low shock stage.

Specimens: 53.4 g including a probe mount on deposit at UNM, Aziz Habibi holds the main mass.