Northwest Africa 12347 (NWA 12347)

Morocco

Purchased: 2017 Feb

Classification: Ordinary chondrite (H5)

Physical characteristics: A dark-brown fusion crust covers the outer edges of the hand sample. The sample appears to be at least moderately weathered due to an overall dark brown appearance and the absence of abundant visible metal grains. The largest chondrule visible in the type specimen has a diameter of 3.5 mm.

Petrography: (J. Laughton, UWO) Model abundances were determined using a combination of optical microscopy and ImageJ software: 74% chondrules, 12% matrix, 6% oxide, 5% metal, and 3% sulphide [+ trace amount of calcium phosphate]. The silicates present include: olivine, orthopyroxene, minor clinopyroxene and plagioclase, and metal (~5%). The sulfide present was in the form of troilite with <0.5 wt.% Ni content. Chondrule diameters ranged in size from 3.5 to 0.1 mm, with an average diameter of 0.4 mm (n = 50). Majority of the chondrules could be discerned, but not all had sharp boundaries. Very minor undulatory extinction patterns were observed in olivine and pyroxene crystals, as well as some minor irregular fractures within the crystals. In thin section ~70% of the metal and troilite has been replaced by a dark red iron oxide (hematite). Oxidation of silicates has also started along the cracks of some crystals.

Geochemistry: (EMPA, M. Beauchamp, UWO) Olivine (Fa_16.7±0.2; Fe/Mn = 29.2±1.0; n=10), Orthopyroxene (Fs_14.6±0.2Wo_1.7±0.0 ; Fe/Mn = 17.8±0.6; n=11) and Plagioclase An_8.8±0.4 (n=10).

Classification: Oridinary chondrite H5, S2, W3.

Specimens: 54.0 g including a thin section at UWO. S. Tutorow holds the main mass.