SAHARA 03500
'Tassa Mahchi'


Primitive Achondrite, ungrouped
(impact melt rock)
standby for nwa s03500 photo
Found February 2003
no coordinates disclosed

A 221.33 g, fusion-crusted, partly broken stone was found in the Sahara Desert by the French team of Caillou Noir under the organization of Michel Franco. A 21.36 g section of Sahara 03500 was provided to the Université Pierre & Marie Curie in Paris (A. Jambon and O. Boudoma; #5272) for analysis, and a smaller 2.0 g sample to the Université Blaise Pascal in Clermont–Ferrand (B. Devouard).

Centimeter-size raised metallic clasts are present over the regmaglypted surface, the result of selective ablation processes on the rounded metal–sulfide globules that occur throughout (~16 vol%). Inside these pyrrhotite globules there is a visible texture resulting from dendritic exsolution of kamacite or taenite. Smaller globules and sub-mm-sized FeNi-metal grains have associated phosphides. The meteorite exhibits an unusual light gray-green color.

The silicate matrix is composed of olivine and orthopyroxene and has an igneous texture consistent with impact-melting and rapid cooling at the surface (Jambon et al., 2005). Small feldspathic glassy shock veins are scattered throughout the meteorite. The bulk composition of Sahara 03500 is similar to that of LL chondrites, but with a higher K/Na ratio, an enrichment in LREE, and a depletion in siderophile elements. An oxygen isotope analysis is currently underway which could help resolve the nature of its parent body.

Sahara 03500 exhibits minor terrestrial weathering (W1) in the form of carbonate veins. The specimen of Sahara 03500 shown above is a 0.80 g ultrathin part slice. Two views of the complete slice from which this specimen was removed can be seen below; the magnified view shows the coarse exsolution (graphic) texture of the large metal–sulfide globules. A photo of the main mass as found is shown courtesy of Michel Franco.

standby for nwa s03500 photo
standby for nwa s03500 photo
Photos courtesy of S. Turecki
standby for nwa s03500 photo
Photo courtesy of Michel Franco