| Price : 4000 $ |
Touat 005 27.747222, -1.369722
Adrar, Algeria
Find: 2020
Classification: Lunar meteorite (feldspathic breccia)
History: These two stones were found by meteorite hunters driving off-road between Tabelbala, Algeria, and the Erg Chech 002 find locality. Nearest towns to this find are Adrar and Tamentit, Algeria.
Physical characteristics: Two stones, identical in appearance, (2035 and 1675 g) were found together. This is a fragmental breccia with white plagioclase megacrysts and lithic clasts set in a dark shocked matrix. Plagioclase megacrysts are up to two centimeters in length and are translucent in thinly sliced slabs. No fusion crust is present.
Petrography: (C. Agee, UNM) Electron microprobe analysis and imaging reveals a fragmental breccia with large, sometimes euhedral anorthite crystals (megacrysts). The megacrysts appear to be shock-mosaicized or recrystallized with a significant amount of dark and light inclusions present, some of the observed inclusion veining in the megacysts is possibly maskelynite. The compositions of the plagioclase megacrysts are slightly more anorthitic than the groundmass plagioclase fragments, although there is compositional overlap between the two that is within microprobe error. This is possibly a monomict breccia since the section analyzed had only one coherent population of pyroxenes and olivines that appear to be related by equilibrium igneous crystallization. The olivine and pyroxene compositions are similar to that in ferroan anorthosites. Shock melt veins with vesicles were observed. Minor opaque phases are ilmenite and chromite.
Geochemistry: (C. Agee, UNM) Plagioclase megacrysts An97.2±0.7Ab2.6±0.3Or0.2±0.1, n=6; groundmass plagioclase An96.5±0.3Ab3.2±0.3Or0.2±0.1, n=6; low-Ca pyroxene Fs28.2±5.9Wo5.6±3.1, Fe/Mn=59±6, n=6; augite Fs18.7±0.4Wo43.2±1.5, Fe/Mn=48±1, n=2; olivine Fa36.7±10.1, Fe/Mn=95±3, n=9; shock melt vein SiO2=43.6±0.4, Al2O3=31.1±0.8, FeO=3.7±0.6, MgO=3.3±0.5, MnO=0.05±0.02, CaO=17.3±0.1, Na2O=0.32±0.05 all wt%, n=3.
Classification: Lunar feldspathic breccia with plagioclase megacrysts. Mafic minerals similar in composition to that present in ferroan anorthosites.
Specimens: 25.8 g on deposit at UNM, Mark Lyon holds the main masses.
