Description
Northwest Africa 12564 (NWA 12564)
(Northwest Africa)
Purchased: 2019 Feb
Classification: Martian meteorite (Shergottite)
History: Purportedly found in Mauritania and purchased in February 2019 by Jaouad Chaoui and Rachid Chaoui from a Mauritanian dealer.
Petrography: (A. Irving and S. Kuehner, UWS) Diabasic texture (mean grainsize ~1 mm). Composed predominantly of complexly-zoned clinopyroxene and maskelynite with accessory titanomagnetite, ilmenite, chlorapatite, merrillite, and pyrrhotite. Myrmekitic intergrowths consisting of silica polymorph + relatively sodic plagioclase are associated with more calcic maskelynite and regions of K-rich glass containing blebs of pyrrhotite are also present.
Geochemistry: Subcalcic augite (Fs22.5-48.6Wo32.2-25.4, FeO/MnO = 30-36, N = 3), ferropigeonite (Fs65.5Wo15.9, FeO/MnO = 39), large maskelynite grains (An48.6-53.0Or2.3-2.0, N = 2), plagioclase in intergrowth with silica polymorph (An34.0Ab62.4Or3.6).
Classification: Shergottite (aphyric, diabasic).
Specimens: 26.5 g including one polished thin section at UWB; remainder held jointly by J. Chaoui and R. Chaoui.
