Meteoritical Bulletin: Entry for Bassikounou

Writeup from MB 92:

Bassikounou 15°47'N, 5°54'W

Bassikounou, Hodh Ech Chargui, Mauritania

Fall: 16 October 2006; 04:00 UTC

Ordinary chondrite (H5)

History: A fireball was witnessed in the area, but no records of the direction of movement were recorded. A single stone of 3165 g was found by A. Salem El Moichine, a local resident, on the same day at 13:00 hr local time, 11 km SE of Bassikounou. The sample for classification was provided to NMBE by M. Ould Mounir, Nouakchott, who obtained it from his cousin who recovered the meteorite. According to S. Buhl (Hamburg, Germany), more than 20 specimens were later recovered by locals and meteorite finders. These finds define a 8 km long strewnfield. The total recovered mass is 46.00 kg.

Physical characteristics: The 3165 g specimen is largely covered by black fusion crust. The interior is light gray. On the surface of the fusion crust there is some adherent soil material, some of which is bright red. Shortly after recovery, the stone was cut into two pieces of 1200 and 1950 g. The larger piece has a rectangular shape and shows indications of flow-lines in the fusion crust.

Petrography: (E. Gnos, MHNGE; B. Hofmann, NMBE, M. Eggimann, Bern/NMBE): Mean chondrule size 0.35 mm (n=53). Metal abundance is 8 vol%, troilite 6.6 vol%. Mean plagioclase grain size is ~20 mm. Troilite is polycrystalline, rich in silicate inclusions, and shows diffuse boundaries to metal. Metal is partly rich in silicate- and troilite inclusions. Rare metallic Cu (10 mm) occurs at kamacite-taenite boundaries and in troilite. Some shock veins and no weathering products were observed.

Mineral compositions: Olivine (Fa_18.6), pyroxene (Fs_16.3 Wo_1.1), plagioclase (An_13.7).

Cosmogenic radionuclides: (P. Weber, PPGUN) Gamma-spectroscopy performed in December-January 2006 showed the presence of the following radionuclides: ⁴⁸V,⁴⁶Sc, ⁵⁶Co, ⁵⁴Mn, ⁵⁸Co, ⁷Be, ⁵¹Cr, ⁵⁷Co, ²²Na, ²⁶Al and ⁶⁰Co. Recalculated to 12 October 2006 ²²Na was 38.0±2.2 and ²⁶Al 31.5±2.1 (both dpm/kg), the activity ratio of 1.21 is fully consistent with a fall on that date.