Mhabes el Hamra        26.2269568°N, 7.8181461°W

Tiris Zemmour, Mauritania

Probable fall: 2018 Dec 23

Classification: Ordinary chondrite (H4/5)

History: Three shepherds (Salek Mohamed, Sidi Ahmed Taleb and Baji Ayoub) were searching for desert truffles in the Tiris Zemmour region of northern Mauritania on December 23, 2018, when they heard a loud sonic boom at 9:30 am. After 36 hours of searching they found five freshly broken stones which fit together to make one complete stone near the village of Mhabes el Hamra. One week later, all of the material was acquired by Aziz Habibi.

Physical characteristics: The recovered pieces (total weight 23100 g) have black fusion crust on exterior surfaces and light gray interiors with abundant fresh metal visible.

Petrography: (A. Irving and S. Kuehner, UWS) Some well-formed, relatively small chondrules occur within a moderately recrystallized matrix containing abundant metal (kamacite plus taenite) and accessory merrillite. The meteorite is texturally transitional between petrographic types 4 and 5.

Geochemistry: Olivine (Fa_18.6-19.1, N = 3), orthopyroxene (Fs_15.9-16.2Wo_1.1.1-1.4, N = 3), clinopyroxene (Fs_5.5.9-6.0Wo_45.2-45.0, N = 2), plagioclase (An_11.3-14.9Ab_83.6-81.6Or_5.1-3.5, N = 2). Cosmogenic radionuclides (Å. Rosén, B. Hofmann, NMBE, GeMSE): Gamma-spectroscopy performed January 30 to February 11, 2019, on a 23.82 g sample showed the presence of several short-lived cosmogenic radionuclides: ⁴⁶Sc, ⁵⁶Co, ⁵⁸Co, ⁷Be ( t_1/2= 53 d; 58.9.6+10.4/-8.4 dpm/kg) and ⁴⁸V (t_1/2= 16 d; 22.9+5.7/-2.6 dpm/kg). Recalculated to December 23, 2018, the ²²Na/²⁶Al activity ratio is 1.98±0.17. The ²⁶Al activity of 41.6+7.8/-2.1 dpm/kg and absence of detected ⁶⁰Co (<0.8 dpm/kg) indicates low shielding.

Classification: Ordinary chondrite (H4/5). Cosmogenic radionuclide results confirm that this is a fresh fall.

Specimens: 20.2 g including one polished thin section at UWB; remainder with A. Habibi.