Northwest Africa 14243 (NWA 14243)

(Northwest Africa)

Purchased: 2019

Classification: Martian meteorite (Shergottite)

History: 3 brownish stone pieces weighing 3280 g (1511+1050+719 g) were found in Mauritania and purchased in 2019-2021 from a Mauritanian dealer Aziz Moudani by a private anonymous collector.

Physical characteristics: Three elongated greenish brownish pieces of stone with almost no crust: 165 × 73 × 75 mm piece weighing 1511 g, 110 × 90 × 67 mm piece weighing 1050 g, and 130 × 5 0x 40 mm weighing 719 g. The interior consists of light brownish-gray, finer-grained matrix.

Petrography: (A. Abdrakhimov, Vernad) Diabasic texture (mean grainsize 0.2-1 mm). In transmitted light, a thin section is seen to be a fine-grained basalt, composed of subhedral grains of clinopyroxene interspersed with almost equal amounts of clear, transparent feldspathic glass (maskelynite) (0.2-1 mm). The analyzed sample contains 50 vol% complexly-zoned Ca-pyroxene (pigeonite and augite), 45 vol% plagioclase (maskelynite) with accessory titanomagnetite (0.1-0.3 mm), ilmenite (~0.1 mm), merrillite (~0.005 mm), chlorapatite(~0.005 mm), pyrrhotite(~0.005 mm), K-Si-rich glasses and orthoclase are also present. Pockets (~0.7 mm) of myrmekitic intergrowths of silica polymorph and sodic plagioclase are associated with maskelynite.

Geochemistry: Mineral compositions and geochemistry: (A. Abdrakhimov, Vernad, SEM/EDS) Subcalcic augite Fs_31.72 (Fs_19.68-43.75, N=18) (Fs_19.68-43.75Wo_36.11-22.32, FeO/MnO = 23.99-36.74, N=18), ferropigeonite Fs_48.56 (Fs_32.58-64.53, N=21) (Fs_32.58-64.53 Wo_10.2-15.88, FeO/MnO = 28.56-36.56, N=21), large maskelynite grains (Ab_43.3-48.3Or_3.4-2.2, N=6), plagioclase in intergrowth with silica polymorph (Ab_59.8-58Or_6.3-6.4 N=2).

Classification: Shergottite (aphyric, diabasic). Sample shows a high level of shock and low level of weathering.

Specimens: Total original mass of 3 samples was 3280 g. Type specimen mass is 106.39 g, includes two polished thin section at Vernad remainder held by DMUH.