Lunar Meteorite: Northwest Africa 13907
from The Meteoritical Bulletin, No. 110
Northwest Africa 13907 (13907)
Classification: Lunar meteorite (anorth)
History: Purchased from Mostafa Hnini in January 2021. Reportedly found in Adrar, Algeria in 2020.
Physical characteristics: Several identically appearing stones found together, no fusion crust, white exterior surface with some tan-colored desert caliche. Saw-cut surface reveals a fragmental breccia of white clasts with some light gray interstitial veins or fine-grained fragments.
Petrography: (C. Agee, UNM) Microprobe examination reveals an anorthitic plagioclase host making up 90-95% of this meteorite. Poikiolitically enclosed in the plagioclase are sparse, small olivine and pyroxene grains (most in the size range 100-200 μm). Larger pyroxene grains are scarce with one larger grain in size range of 1 mm observed in the microprobe mount. Together, olivine and pyroxene make up a total of ~5% of this meteorite.
Geochemistry: C. Agee, UNM) Olivine Fa38.8±0.7, Fe/Mn=86±6, n=4; low-Ca pyroxene Fs30.8±0.1Wo2.9±0.1, Fe/Mn=55±4, n=4.
Classification: Lunar ferroan anorthosite (FAN), brecciated. Olivine, pigeonite and plagioclase compositional values plot within the FAN suite field (after Warren, 1993).
Specimens: T20 g on deposit at UNM, Matthew Stream holds the main mass.
I have not studied NWA 13907. Like most feldspathic lunar meteorites (e.g., Dhofar 490/1084 or the NWA 8222 clan), the rock consists of clasts of ferroan anorthosite (the whitest clasts) and older feldspathic (anorthositic) breccias (“breccia within breccia”) set in a fragmental or melt matrix..
Meteoritical Bulletin Database
Warren P. H. (2022) Ferroan anorthosite: A widespread and distinctive, high-olivine/pyroxene, lunar rock type. 85th Annual Meeting of The Meteoritical Society, abstract no. 6047.