Northwest Africa 10140 (NWA 10140)

(Northwest Africa)

Purchased: 2015 Feb

Classification: Lunar (troctolitic anorthosite)

History: Purchased by Larry Atkins in Morocco in February 2015.

Physical characteristics: Single stone. A saw cut reveals a very fine-grained, light-gray groundmass, crosscut by numerous shock melt veins some up to 3 mm.

Petrography: (C. Agee, UNM) This meteorite is a fine-grained anorthositic troctolite (Prinz and Keil, 1977) with plagioclase (75%), olivine (15%), and low-Ca pyroxene (10%) as dominant silicate phases. There are numerous shock melt domains present, some with quench spinifex textures. Accessory troilite and chromite were observed.

Geochemistry: (C. Agee and N. Muttik, UNM) olivine Fa_23.4±2.8, Fe/Mn=90±4, n=11; low Ca pyroxene Fs_20.5±1.1Wo_3.7±0.9, Fe/Mn=56±6, n=9; plagioclase An_97.1±1.0Ab_2.7±1.0Or_0.2±0.0, n=5; Shock melt (20 μm defocused electron beam, proxy for bulk meteorite composition): SiO₂=42.1±0.3, TiO₂=0.13±0.04, Al₂O₃=27.3±3.1, Cr₂O₃=0.11±0.04, MgO=7.8±2.7, FeO=4.4±1.5, MnO=0.05±0.02, CaO=15.4±1.4, NiO=0.00±0.00, Na₂O=0.27±0.03, K₂O=0.00±0.00 (all wt%), Fe/Mn=89±35, Mg#=75.9±0.8, MgO+FeO=12.1±4.2 (wt%), n=12.

Classification: Lunar (troctolitic anorthosite) based on Stoeffler et al. (1980).

Specimens: 14 g including a probe mount on deposit at UNM, Larry Atkins holds the main mass.