Northwest Africa 8645 (NWA 8645)

(Northwest Africa)

Purchased: 2014 Mar 7

Classification: Ordinary chondrite (L5)

History: Donated to Cascadia by Dick Pugh, who purchased the meteorite on March 7, 2014, from Edwin Thompson, who obtained the sample from a Moroccan trader.

Physical characteristics: A faceted medium brownish gray specimen has remnant patches of fusion crust on its exterior. A large (>1 cm) discrete, light-colored inclusion is visible on an exterior surface.

Petrography: (A. Ruzicka and M. Hutson, Cascadia) Two light-colored regions containing euhedral olivine grains typical of an igneous lithology occur along edges of the thin section. The chondritic host is darkened by weathering product and an orange staining of the silicates. Chondrules are readily identifiable, with partially integrated margins and lacking glass in their interiors. Feldspar grains are typically 10-30 μm across. Eighteen out of 23 olivine grains examined have mosaic extinction and 2 sets of planar fractures. Isolated small patches of shock melt are present.

Geochemistry: Olivine (Fa _26.2±1.0, N=34), low-Ca pyroxene (Fs_22.4±1.6Wo_1.9±0.5, N=14), feldspar (Ab_80.1±1.7Or_8.3±2.4An_11.6±1.9, N=10).

Classification: Based on the texture and composition, this is an L5 ordinary chondrite.

Specimens: Cascadia holds the entire sample which includes 44.7 g and 1 polished thin section.