Mreira

Mauritania
Fall, 16.12.2012

Ordinary chondrite, L6
A group of complete pieces, total weight around 450g

Remarks: Pieces have fresh black crust. On a broken face you can see fine white matrix with black shock veins.

History:
According to Ait Hiba Abdelhadi, a fireball was seen in the afternoon sky on December 16, 2012, several school children saw the fireball explode and detonations were heard near the village of Mehaires, Western Sahara. Pieces were recovered approximately 40 miles south of Mehaires, near Mreïra, Mauritania, only a few days after the event. The strewn field is in the area called “Stailt Omgrain”, which is a local nomadic name. This is south of Mehaires and north of the mountain “Galbe lahmar”. Therefore this is a possible fall associated with the fireball of December 16, 2012.

Physical characteristics:
The largest single piece weighed 602 grams and was completely covered with fresh fusion crust. A total of approximately 6 kg of freshly crusted stones were recovered. Vincent Jacques hold the main mass, weight 1111,1 g

Petrography:
(C. Agee, UNM) Microprobe examination of two polished surfaces shows brecciation and numerous fractured silicate grains, scattered equilibrated chondrules, shock-melt pockets, kamacite, troilite, and merrillite. Fresh, vesiculated fusion crust ~200 um thick.
Mineral compositions and Geochemistry: (C. Agee and L. Burkemper, UNM) Olivine Fa24.4±0.2, Fe/Mn= 47±3, n=8; low-Ca pyroxene Fs20.3±0.1Wo1.5±0.1, Fe/Mn= 28±1, n=7; plagioclase Ab82.7±2.0An10.4±0.6Or6.8±1.4, n=4.

Classification:
Ordinary chondrite (L6), weathering grade (W0), shock grade (S6)

Specimen description:
Pieces have fresh black crust. On a broken face you can see fine white matrix with black shock veins.

References:
Meteoritical Bulletin Database