Northwest Africa 10454 (NWA 10454)

(Northwest Africa)

Purchased: Feb 2004

Classification: Ordinary chondrite (L5/6)

History: Purchased by Dick Pugh from a Moroccan trader during the February 2004 Gem and Mineral Show in Tucson, Arizona. Pieces were donated to Cascadia in 2004 and the remaining mass in 2014.

Physical characteristics: Fragmented hand specimen partly covered with a thin fusion crust and partly covered by caliche. Cut and polished face reveals lighter-colored granoblastic clasts cut by veins, set in a larger portion of darker host that includes chondrules and fragments and small patches of apparent dark-gray shock melt.

Petrography: Host consists of numerous, readily delineated chondrules (0.71±0.35 mm diameter) set against a translucent to transparent matrix. Somewhat coarse feldspar (length 51±23 μm, range 23-123 μm, N=43) within and around chondrules. Rust stains occur around metal (~6% overall in rock), but metal is largely unaffected by weathering.

Geochemistry: (K. Farley and A. Ruzicka, Cascadia) Olivine (Fa_25.9±0.8, Fe/Mn = 49.0±4.5 at., N = 27), low-Ca pyroxene (Fs_21.7±0.3Wo_1.9±0.1En_76.5±0.3, Fe/Mn = 29.0±2.3 at., N = 23), feldspar (Ab_83.8±1.0An_11.5±1.1Or_4.7±1.1, N = 6).

Classification: L5/6 based on mineral chemistry, metal content, chondrule size, and textures. Feldspar grain size consistent with type 5/6 transition.

Specimens: Cascadia holds the entire sample which includes two specimens of mass 214.9 g and 22.5 g, as well as one polished thin section and one potted butt.