Northwest Africa 10580 (NWA 10580)

(Northwest Africa)

Purchased: October 2015

Classification: Carbonaceous chondrite (CO3)

History: Purchased from a Moroccan dealer, October 2015.

Physical characteristics: Many identical appearing stones. Shiny, black to dark brown, smooth weathered exterior with very small chondrule pits; saw cuts reveals numerous 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, a few up to 600 μm. Scattered metal/sulfide blebs, fine-grained matrix makes up about 50% of this meteorite. Most chondrules appear to be Type I with forsteritic olivine, enstatitic pyroxene or aluminous diopside. Very few Type II chondrules were observed.

Geochemistry: (C. Agee and M. Spilde, UNM) All chondrule olivine Fa_9.5±17.5, Cr₂O₃=0.33±0.16, n=20; Type I chondrule olivines Fa_0.7±0.2, Cr₂O₃=0.27±0.16, n=11; ferroan chondrule olivines ranged from Fa_2-59 with an average of Fa_21.9±23.0, Fe/Mn=78±58, Cr₂O₃=0.41±0.14, n=9; Type I chondrule low-Ca pyroxene Fs_1.3±0.4Wo_1.5±1.7, n=5; Type II chondrule low-Ca pyroxene Fs_20.6±18.8Wo_1.6±1.8, Fe/Mn=69±20, n=2; aluminous diopside Fs_3.2±0.8Wo_39.7±16.5, n=2.

Classification: Carbonaceous chondrite (CO3), likely type 3.0 based on mean value and sigma of Cr₂O₃ in ferroan olivine (Grossman and Brearley, 2005), however there were too few Type II chondrules present (n=9) in the probe section to obtain good statistics.

Specimens: 21.73 g including a probe mount on deposit at UNM, Gary Fujihara holds the main mass.