5.8 grams. CH/CBb
TKW 16 kg.Fall not observed. Found October 2003, Bashkortostan, Russia.
Daniel writes:
From the MetBul:
A stone, weighing 16 kg, was found by a tractor driver in a field during the harvest, in the Ishimbai area, in Bashkortostan, near the village of Isheyevo. A small piece of meteorite was delivered to the Vernadsky Institute by Kazakov DA and Polozkov AG, September 2004. Mineralogy and classification (Ivanova MA Vernad., Ulianov AA, MSUM). The melting crust is well developed, dark brown. The meteorite is composed of metal grains of FeNi, C, POP, rare BO chondrules (size 0.02-1 mm), fragments of chondrums, CAI and matrix lumps. The FeNi metal comprises from 50 to 70% by volume and contains 4.2 to 8.4% by weight of Ni, 0.2 to 0.5% by weight of Co and 0.03 to 0.6% by weight of Cr; The Co / Ni ratio is approximately solar. C-chondrules do not contain metallic FeNi grains, they are rich in Mg and consist of cryptocrystalline materials rich in pyroxene. Olivine, Fa 2.5, rare olivines rich in FeO, Fa 10-38; pyroxene, Fs 2.1 Wo 1.7, pyroxene rich in FeO, Fs 8-12 Wo 0.8-1.8; the troilite is rich in Cr, 2.5% by weight of Cr. INAA data for a 20 mg chip: 2.74% by weight Ni; 717 ppm Co; 2608 ppm Cr, 8.2 ppm Sc and 1.59 ppm Ir. Petrological Type 3; shock stage, S1; grade of alteration, W1.
A team from the Museum of Mineralogy and Cosmochemistry of the Museum (UMR 7202 MNHN / CNRS) associated with researchers from the University of Florence (Italy), the Laboratory of Structures and Properties of the Solid State and the Laboratory of Planetology of Grenoble, reports, in an article to be published this week in the PNAS, the discovery of a strange inclusion in the meteorite of Isheyevo. The mineralogy of this inclusion (anhydrous silicates of magnesium and iron) is similar to that of some Antarctic or stratospheric micrometeorites. It could indicate a cometary origin. However, this inclusion measures ~ 0.5 mm and therefore has a volume 30000 times higher than micrometeorites.
Measurements made with NanoSIMS have shown that this inclusion, called PX18, has an isotopic composition of nitrogen (proportion of various isotopes of nitrogen) extremely variable. It is, in particular, 4 times richer locally in heavy nitrogen (15N) compared to the isotopic composition of the Earth. This enrichment is the largest ever observed in extraterrestrial matter. Areas rich in 15N correspond to organic matter. These enrichments in 15N will allow researchers to better understand the mechanisms of formation of the organic matter of meteorites. It is possible that complex phenomena of irradiation by the protosoleil (ancestor of the sun) have generated this abnormal isotopic composition. The discovery of this inclusion poses many problems to the current models of solar system formation. |