Mahbas Arraid ( 39,765 g )

Mahbas Arraid        27°38.333’N, 9°28.124’W
Guelmim Smara, Western Sahara
Probable fall: 2013 Dec 9
Classification: Ordinary chondrite (LL6)
History: (H. Chennaoui Aoudjehane FSAC, H. Lharbi) A fireball fall was reported in the southern part of Morocco by many eyewitnesses from Assa, Zag and Al Mahbes area on 9 December 2013 around 6:30 pm GMT. Ali Houmida, Cheggef, Jdi and many other Moroccan hunters, as well as people from the area, saw the fireball lasting several ". Collection of the testimonies of the fireball and their conciliation indicate a bolide moving from the northeast to southwest. The meteor terminated above the area south of Mahbas Aaraid. Three sonic booms were reported. Meteorite hunters traveled to the expected fall site as indicated by meteor termination. No meteorites were found, and hunting was stopped after a few days. In the beginning of September 2014 (nine months latter after the fireball), Fatma, a young nomad girl found two black stones, totally different from all the other rocks in the area. After news of the find spread, several meteorite hunters returned to the area and collected more pieces. Samples of this meteorite were sent to the Hassan II University of Casablanca Morocco by H. Lharbi on 30 December 2014 for classification. To date, the total known mass is about 5500 g. The meteorite is known under the name of "Al Mahbes" by Moroccan hunters.
Physical characteristics: Many fresh full stones with fusion crust. The interior is brecciated with clear and dark-gray clasts surrounded by lighter-colored regions. Neither troilite nor metal grains are clearly visible.
Petrography: Polished mount shows recrystallized matrix with a few poorly defined barred chondrules. Olivine and opx are fractured (mm-sized clasts). Plagioclase occurs as irregular grains to 0.1 mm. Troilite and taenite are evenly distributed in grains to 0.1 mm. Accessory chromite and ilmenite.
Geochemistry: Olivine Fa26±0.4 (N=15); Opx Fs25±0.2Wo2±0.3 (N=11); Cpx Fs10±1Wo44±1 (N=5); plagioclase An10±0.2Or5±1 (N=7); taenite Ni52. Short-lived cosmogenic isotopes were measured by P. Weber at La Chaux de Fonds (La Vue-des-Alpes underground laboratory, Switzerland; Gonin et al 2003). Measurement was on a sample of 27.23 g during 6 days in April 2015, 478 days after the fireball. Long- and short-lived cosmogenic radionuclides were measured. The presence and amount of short-lived isotopes support a fall around the time of the witnesses fireball. 26Al 43.6±2.2, 22Na 79.4±4.5; 54Mn 47.1±3.2, all calculated at 9 December 2013; the other short lived isotopes: 57Co <1.5; 46Sc <1.0; 56Co <3.0; 58Co <0.8; 51Cr <6.2; 48V <1.3. The 22Na/26Al ratio calculated at the time of the fireball 1.82 (compared to Mreira 2.4 or Tissint 2.3) is compatible with the estimated time of fall. The activity of the cosmogenic isotopes was calculated according to the method described in Weber et al. (2017), with 3-sigma statistical errors. A 10% additional systematic uncertainty is estimated.
Classification: LL6, brecciated
Specimens: 26 g (21.4+3.9+1.6) provided by Hamza Lharbi and 24.1 g provided by Aaras Jonikas to FSAC.
 
 
State/Prov/County:
Guelmim Smara
Date:
2013 Dec 9
Latitude:
27°38.333'N
Longitude:
9°28.124'W
Mass (g):
~5500
Pieces:
Many
Class:
LL6
Shock stage:
S4
Weathering grade:
W0
Fayalite (mol%):
26±0.4 (n=15)
Ferrosilite (mol%):
25±0.2 (n=11)
Wollastonite (mol%):
2±0.3
Magnetic suscept.:
3.7
Classifier:
H. Chennaoui Aoudjehane, A. Jambon
Type spec mass (g):
51
Type spec location:
FSAC
Main mass:
Aaras Jonikas
Finder:
A nomad girl named Fatma
Comments:
Submitted by H. Chennaoui Aoudjehane