Northwest Africa 15050 (NWA 15050)

Algeria

Purchased: 2014

Classification: HED achondrite (Eucrite, melt breccia)

History: Several meteorites were reportedly collected at a strewn field and purchased by Mohamed Aid. One of these stones was provisionally named NWA 8419. Yet, the name was later discontinued when it turned out that the type specimen was in fact part of the Aouinet Legraa fall (unbrecciated Eucrite, 2013). Another stone was subsequently purchased by Dmitry Kachalin from Mohamed Aid. Further investigation by G. Makhatadze and K. Vlasov (Vernadsky Institute) revealed that this stone initially sold as "NWA 8419," now in possession of Dmitry Kachalin, did not match the petrographic description of Aouinet Legraa. The stone is heavily brecciated with signs of terrestrial weathering.

Physical characteristics: The type specimen exhibits no fusion crust. The gabbroic clasts (to 1 cm) and surrounding dark melt show signs of weathering.

Petrography: (K. Vlasov, UBayr) Coarse-grained monomict breccia, consisting of gabbroic clasts with subophitic texture surrounded by dark glassy veins. Major phases in gabbroic clasts: 45 vol% low-Ca pyroxene (crystal size 0.1-0.4 mm) with exsolution lamellae, 20 vol% augite and 30 vol% plagioclase (crystal size 0.2-0.5 mm). Minor phases: ilmenite, chromite, troilite, and zircon. Products of alteration include gypsum and barite veins and secondary iron-rich minerals.

Geochemistry: Low-Ca eucritic pyroxene (Fs_59.3±1.6Wo_3.1±2.0 , FeO/MnO = 31±2, n = 31) with high-Ca pyroxene exsolution lamellae (Fs_40.7±3.9Wo_25.4±5.9, FeO/MnO = 29±2, n = 3), augite (Fs_26.3±1.2Wo_42.8±1.1, FeO/MnO = 30.2±2.8, n = 16) and plagioclase (An_89.8±0.8Or_0.2±0.1, n = 15).

Classification: Eucrite melt breccia

Specimens: 13.8 g including 1 polished mount at UBayr; remainder with Dmitriy Kachalin (kamnisneba.ru)