Gueltat Zemmour        25°05’32.0’’N, 12°37’23.9’’W

Boujdour, Morocco

Fall: 21 Aug 2018

Classification: Ordinary chondrite (L4)

History: (H. Chennaoui Aoudjehane FSAC, UH2C, Ahmed Bouferra, Mohamed Aid, "Moroccan association of meteorites"). On 21 Aug 21 2018 around 14:20, many people from the south of Morocco saw a bright fireball. In Smara, Seddiki Mbarek reported the passing of a fireball similar to a yellow-white shining star, moving from the northeast to southwest, in the direction of Gueltat Zemmour. His son Aboubakr also saw the fireball, saying that his sighting only lasted a few seconds before a building blocked the view. Abderrahmane Latifi and his son Adil, also from Smara, both saw a fireball shining red, then yellow, brighter than the Sun, lasting about 3 s. In the fall area, Mahjoub Boutabâa, a nomad, was inside his tent; he heard a sound similar to the explosion of a mine, followed by a few sonic booms that resonated in the entire Oued Labiyad valley, similar to thunder. Abba Essahed, another nomad, and his wife Basaddouk Aicha were out of their tent when they heard a whistling sound almost identical to ocean waves, then five sonic booms akin to the explosion of a mine, making them feel like the mountains would crumble. They saw a very bright fireball comparable to a burning 4x4 vehicle in terms of size, first red then yellow, more dazzling than the Sun, with a flashing light moving from north to south for a few seconds. There was smoke in the sky directly above them. Aicha was so scared that she went to hide between the water barrels. All testimonies are concordant on the date and the time of August 21 around 14:20. Due to the period of the fall (one day before "Aid El Adha"), hunters could not search immediately. Searching began ten days after the fall and the first pieces were found in mid-September, about three weeks after the fall, a few km to the west of Gueltat Zemmour. A group of hunters: Mohamed Ouicha, Brahim Ouhra, Mbarek Amediaz, Aissa Ouicha and Brahim Ouaadjou found many pieces (5.1, 5.0, 6.3, 7.2, and 15 g) in a valley between Wad Awzireft and Wad Labiyad (N25°05’32.0’’; W12°37’23.9’’) and north of Koudiat Rjilya. Bigger pieces were found SW of this site (N24°53’29.52"; W12°42’10.5’’ ; around 700 g) (N24°56’37.06"; W12°40’52.12’’; around 200 g). The direction of the fall was NNE-SSW and the strewnfield is about 12 km.

Physical characteristics: A few small pieces totalling around 500 g and 3 bigger ones (5448 g, 1374 g and 426 g) not weathered, totally covered by a black matte fusion crust, showing fine  grains, very friable material, and easily discernable chondrules. Large pieces are broken and show a gray-colored interior; they are partially covered by fusion crust.

Petrography: (H. Chennaoui Aoudjehane UH2C, L. Folco UniPi) Numerous well-defined chondrules (POP, PO, GPO, PP, RP and glassy chondrules) up to 3 mm. Plagioclase is very small (2 µm maximum). Mesostasis is microcrystalline. Most metal and sulfides are automorphous grains, um sized, to large grains up to 500 um; they occur inside chondrules as small grains, in the mesostasis as small and large grains, and surrounding some chondrules.

Geochemistry: (V. Moggi Cecchi, UniFi, H. Chennaoui Aoudjehane UH2C) Olivine Fa_26.0±0.7 Fe/Mn=51.23 (N=10), low-Ca pyroxene Fs_20.7±0.8Wo_1.1±0.5 Fe/Mn=28.51 (N=7), plagioclase An_8.2±2.4Or_4.8±0.8 (N=3), Taenite Ni 50.3±2.7 (N=3) Whole-rock trace-element concentrations by ICP-MS (M. D’Orazio, UniPi): V 59, Cr 2799, Ni 10115, Co 399, La 0.329, Ce 0.879, Pr 0.138, Nd 0.645, Sm 0.211, Eu 0.088, Gd 0.284, Tb 0.054, Dy 0.364, Ho 0.081, Er 0.242, Tm 0.035, Yb 0.236, Lu 0.038 (units = µg/g). Cosmogenic radionuclides: (Å. Rosén, B. Hofmann, NMBE,  GeMSE): Gamma-spectroscopy performed in October 2018 on a 21.74 g sample showed the presence of several short-lived cosmogenic radionuclides (⁵⁷Co, ⁴⁶Sc, ⁵⁶Co, ⁵⁸Co, ⁷Be ( t_1/2= 53 d; 84.6±10/-7 dpm/kg) and ⁴⁸V (t_1/2= 16 d; 17.8±4.6/-5.4 dpm/kg). Recalculated to August 21, 2018 the ²²Na/²⁶Al activity ratio is 1.69±0.1. These data confirm that it is a fresh fall. The ²⁶Al activity of 55.5±3.6/-3.1 dpm/kg and absence of detected ⁶⁰Co (<0.8 dpm/kg) indicates only a few cm of shielding.

Classification: L4

Specimens: A sample of 20.1 g provided by the "Moroccan association of meteorites", small pieces totaling 30 g provided by Aaronson, FSAC. Aaranson: 1374 + 426 g; Mohamed Aid: 5448 g; Private collector, Casablanca: 21 + 7.2 + 6.3 + 5.1 + 5 g.