Northwest Africa 12592 (NWA 12592)
Classification: Lunar (frag. breccia)
History: A single weathered stone lacking a fusion crust was found by nomads in Algeria and purchased by Dustin Dickens in Nouakchott, Mauritania in 2017 from an anonymous meteorite dealer.
Physical characteristics: Dark grey sandblasted exterior, with many irregular shaped fragments set in a fine grained vesiculated groundmass. No fusion crust.
Petrography: (T. S. Hayden, M. Anand, OU) The meteorite is a clast-rich fragmental breccia containing numerous mineral and lithic fragments embedded in a fine-grained vesiculated (regolith) matrix. The lithic clast population consists primarily of basaltic clasts, dominated by Ca-rich pyroxene and plagioclase, with minor olivine components. The size range of the lithic clasts is 0.19-1.9 mm. Mineral clasts are mainly pyroxene, olivine, plagioclase, chromite, troilite and Fe-Ni phases. Some impact melt textures present also.
Geochemistry: Mineral Composition and Geochemistry: (T. S. Hayden, M. Anand, OU) Feldspar (An95.2 ± 0.7Ab4.7 ± 0.7, N = 31), Pigeonite (Fs43±3.3Wo9.5±4.4, Fe/Mn=65.5±3.3, N=45), Augite (Fs25±4.8Wo35.7±6.1, Fe/Mn=59.5±5.6, N=54), Clinoferrosilite (Fs48.6Wo5, Fe/Mn = 67.4, N=1), Clinoenstatite (Fs44.5±4.3Wo4.4, Fe/Mn = 64.7±3.9, N=11), Olivine (Fa47.6±16, Fe/Mn=104.5±10.8, N=33). O isotopes (measured at OU): Repetition 1: δ17O = 3.266‰, δ18O = 6.333‰, Δ17O=-0.052 (linearized using a slope of 0.5247), Repetition 2: δ17O = 3.217‰, δ18O = 6.174‰, Δ17O=-0.018‰ (linearized using a slope of 0.5247. Mean: δ17O = 3.242 ± 0.035‰ (1-sigma), δ18O = 6.254 ± 0.112‰ (1-sigma), Δ17O=-0.035±0.024 (1 sigma).
Classification: Lunar fragmental regolith breccia
Specimens: Specimen: 20 g specimen held at OU. Dustin Dickens holds the main mass.