NWA 8261 Achondrite Eucrite Fragment weighing 0.99g

Northwest Africa 8261 (NWA 8261)

(Northwest Africa)

Purchased: 2014 Jan

Classification: HED achondrite (Eucrite, polymict)

History: Purchased by Kuntz in January 2014 from a dealer in Erfoud, Morocco.

Petrography: (A. Irving and S. Kuehner, UWS) Polymict breccia composed predominantly of crystalline debris related to sparse lithic clasts of gabbroic eucrite, along with rare clasts of much finer grained, intersertal-textured eucrite, autolithic breccia clasts (i.e., breccia within breccia), and rare fragments of diogenitic orthopyroxene. Gabbroic eucrite clasts consist of exsolved pigeonite and polycrystalline calcic plagioclase with accessory silica polymorph, ilmenite, chromite, troilite and barite. Isolated grains of olivine, more ferroan augite, and ferroan pigeonite are also present.

Geochemistry: Diogenitic orthopyroxene (Fs_23.9Wo_2.3, FeO/MnO = 27), host orthopyroxene (Fs_60.2Wo_3.2, FeO/MnO = 32), clinopyroxene exsolution lamellae (Fs_28.9Wo_41.4, FeO/MnO = 29), olivine (Fa_54.0, FeO/MnO = 45), ferroan augite (Fs_35.0Wo_40.0, FeO/MnO = 29), ferroan pigeonite (Fs_62.0Wo_24.2, FeO/MnO = 30).

Classification: Eucrite, polymict breccia.

Specimens: 20.9 g including a polished thin section at UWB. The remainder is held by Kuntz.