Northwest Africa 090 (NWA 090)

(Northwest Africa)

Purchased: 2000

Classification: Primitive achondrite (Acapulcoite)

History: A 30 g meteorite was purchased by Michael Farmer from a Moroccan meteorite dealer in Erfoud, Morocco, in 2000.

Physical characteristics: A rounded stone covered by a well-developed fusion crust. Interior is fine grained with even distribution of small metal and troilite grains.

Petrography: (C. Ostrander, Z. Torrano, ASU) Proto-granular texture dominated by pyroxene, olivine, Fe-Ni metal, and troilite. Uniform grain size near 200 μm. Section shows several rounded mineral aggregates (~400 μm). The rounded aggregates are dominated by pyroxene, one with a radial texture. Holly-leaf-shaped Fe-Ni metal grains, some peppered with sub-μm inclusions. Fe-Ni metal distribution is not homogeneous. Troilite dominantly single crystal, showing uneven distribution with metal. Crystals typically and lacking 120º junctions. Shock is low.

Geochemistry: Olivine Fa_6.1±0.3, FeO/MnO = 10.7-15.4, Cr₂O₃ = 0.01-0.07 wt.%, n=4; low Ca pyroxene Fs_7.3±0.3Wo_1.2±0.3, FeO/MnO = 7.9-14.0, n=4; high Ca pyroxene Fs_3.4±0.2Wo_45.9±0.2, n=5; and, plagioclase An_12.7±0.2Or_5.4±0.1, n=5. Accessory chromite, Cr/[Cr+Al] = 0.89-0.91.

Classification: Acapulcoite, medium weathering, low shock

Specimens: 12.6 g, one polished thin section and a polished thick section are on deposit at ASU.