Northwest Africa 10313 (NWA 10313)

(Northwest Africa)

Purchased: February 2015

Classification: Ordinary chondrite (L6)

History: Purchased from Horst Burkhard in Tuscon in Feb 2015 as an unclassified NWA meteorite, and a portion subsequently donated to Cascadia.

Physical characteristics: Partly fusion crusted individual, broken surfaces mostly have dark patina, one cut face shows chondritic texture with metal that locally forms vein-like segments. There are rust haloes surrounding the metal grains. Fusion crust is very thin and reveals underlying chondritic texture.

Petrography: (M. Ream and A. Ruzicka, Cascadia) Chondrules are poorly defined and large (diameter 1.5±0.6 mm, N = 18) and are set in mostly transparent, coarse matrix, with secondary feldspar grain sizes exceeding 50 μm. Moderate mosaicism and planar fracturing in olivine indicates shock grade S4. Contains ~4-5% metal and ~3% troilite.

Geochemistry: Olivine, Fa_25.5±0.3 (Fa_24.9–26.2, N = 22); low-Ca pyroxene, Fs_21.7±0.7Wo_1.6±0.3 (Fs_20.9-24.0Wo_1.1–2.1, N = 27).

Classification: L6 chondrite based on mineral composition, metal content, and texture, although chondrule size relatively large.

Specimens: Cascadia holds a 39.5 g slab, a 3.6 g slice, a 0.5 g slice, a polished thin section, and a potted butt. Art Johnstone holds the main mass.