Northwest Africa 10900 (NWA 10900)

(Northwest Africa)

Purchased: 2015

Classification: Ureilite

History: Purchased in 2015 by Brahim Tahiri in Morocco and sent to his partner Sean Tutorow for analysis.

Physical characteristics: Single stone with no fusion crust, irregular exterior surface. A sawn surface shows a mosaic of gray-colored silicate grains.

Petrography: (C. Agee, UNM) This meteorite has predominantly olivine and pigeonite. The olivine grain boundaries contain fine-grained iron metal and oxidized iron. Silica-rich melt inclusions are present. Graphite is ubiquitous. No plagioclase was detected.

Geochemistry: (C. Agee and M. Spilde, UNM) Olivine cores Fa_22.5±0.1, Fe/Mn=50±4, Cr₂O₃=0.68±0.03 (wt%), CaO=0.37±0.03 (wt%), n=4; olivine reduction rims Fa_8.5±0.7, Fe/Mn=16±0, Cr₂O₃=0.96±0.12 (wt%), CaO=0.44±0.02 (wt%), n=2; Pigeonite Fs_17.0±2.4Wo_11.3±3.2, Fe/Mn=27±3, n=5; pigeonite reduction rim Fs_9.3Wo_15.7, Fe/Mn=10, n=1.

Classification: Ureilite based on iron reduction in rims and grain boundaries of olivines, Cr₂O₃ and CaO content of olivine, typical ureilite mineralogy of olivine + pigeonite, and presence of graphite.

Specimens: 20.54 g including a probe mount on deposit at UNM, Sean Tutorow holds the main mass.