Northwest Africa 13774 (NWA 13774)
(Northwest Africa)
Purchased: 2021
Classification: Mesosiderite
History: The meteorite was purchased from a group of meteorites hunters in Nouadhibou, Mauritania, in early 2021.
Physical characteristics: Four brownish fragments partly covered with fusion crust.
Petrography: The meteorite displays a light-brownish interior and is composed of silicate (about 60 vol%) and metallic (about 40 vol%) portions. The silicate fraction is predominantly composed of exsolved pyroxene, up to 2 mm sized compositionally zoned low-Ca pyroxene, olivine, and calcic plagioclase. Olivine often contains symplectic intergrowths of low-Ca pyroxene and chromite. Minor phases are silica, Ti-chromite, FeS, and merrillite. The metallic portion consists mostly of kamacite, with some taenite.
Geochemistry: zoned low-Ca pyroxene: Fs21.9±2.1Wo1.9±0.9 (Fs19.5-25.1Wo0.9-3.1, FeO/MnO=26-33, n=7); low-Ca pyroxene host crystals to augite exsolutions: Fs31.5±0.2Wo4.1±0.2 (Fs31.1-31.8Wo3.7-4.3, FeO/MnO=24-26, n=8); augite exsolutions: Fs16.3±0.2Wo40.0±0.6 (Fs16.0-16.8Wo38.8-40.6, FeO/MnO=19-25, n=8); olivine: Fa29.3±0.4 (Fa28.8-29.9, FeO/MnO=41±2, n=9); calcic plagioclase: An90.2±2.0 (An87.1-93.5, n=10)
Classification: Mesosiderite
