Northwest Africa 12911 (NWA 12911)

(Northwest Africa)

Purchased: 2003

Classification: Ordinary chondrite (L6)

History: Baird purchased at a meteorite auction in Tucson in 2003, and donated an end piece to Cascadia in 2013.

Physical characteristics: The exterior of the end piece is covered by a dark brown/black fusion crust and is faceted. The cut face is polished; most of the face is dark brown, lacks readily defined chondrules, and contains almost no visible metal/sulfide grains. One side of the cut face is light gray and contains moderately abundant metal/sulfide grains.

Petrography: (M. Hutson, A. Ruzicka, W. Fish, Cascadia): The texture of the silicates in thin section are relatively well-integrated; indistinct chondrules are visible. Plagioclase feldspar grains up to 70 microns across are present. Approximately 60-70% of metal and sulfide grains have been replaced.

Geochemistry: Mineral compositions and geochemistry: Olivine and pyroxene grains are equilibrated: Fa_25.7±0.5, N=14; Fs_21.4±0.1Wo_1.6±0.2, N=13.

Classification: Ordinary chondrite (L6) based on chemistry and texture.

Specimens: Cascadia holds 22.2 g in two pieces, in addition to two polished thin sections and a mounted butt. The main mass is held by Baird: Jerry Baird, Lake Havasu City, AZ.