Northwest Africa 5890 (NWA 5890)

(Northwest Africa)

Purchased: 2009

Classification: Primitive achondrite (Winonaite)

History: The meteorite was purchased from a local meteorite dealer in Erfoud, Morocco.

Physical characteristics: Thirty-six up to 1 cm sized brownish fragments without fusion crust.

Petrography: Sawn surfaces of the fragments show that the meteorite is composed of larger metal-dominated and less abundant silicate-rich regions. Silicate regions display a recrystallized texture dominantly composed of typically 100 to 200 μm sized enstatite, forsteritic olivine, augite, and feldspar grains, with enstatite being the most abundant mineral phase. 120 degree triple junctions are abundant. Metal is kamacite and taenite and has been partly altered to reddish-brownish iron oxides and hydroxides; contains some troilite. Chondrules were not observed.

Geochemistry: olivine: Fa_4.0±0.1 (Fa_3.8-4.0, FeO/MnO=23±2, n=4); low-Ca pyroxene: Fs_6.0±0.2Wo_1.7±0.1 (Fs_5.7-6.2Wo_1.6-1.7, FeO/MnO=27±4, n=4); Ca-pyroxene: Fs_2.2±0.2Wo_46.4±0.3 (Fs_1.9-2.4Wo_46.1-46.7, n=5); feldspar: An_10.5±1.0Ab_87.4±0.9Or_2.2±0.2, n=3

Classification: Winonaite (metal rich)