Degtevo        49°09.6’N, 40°39.7’E

Rostovskaya oblast’, Russia

Confirmed fall: 20 March 2016

Classification: Ordinary chondrite (H5)

History: Imamkulov Toir Mamazoirovich was working on a farm near Degtevo when he heard a whistling sound and saw a stone falling. Slezhuk Dmitry Vasilyevich, working on the same farm, also heard a loud whistling sound from the sky, went to the place of the fall and saw the piece. Several other people working on the farm confirm having heard a whistling sound and a trace in the sky. The first two aforementioned witnesses live in the town of Millerovo. A single piece of 2092 g and a fragment of 5.85 g were retrieved. Find information collected by Dmitry Sadilenko, Russian Academy of Sciences. The complete mass was purchased at the Ensisheim show 2016 by Marc Jost, Switzerland.

Physical characteristics: Single stone with dimensions 19.3 × 13.5 × 6.5 cm. This is an oriented meteorite with well-developed regmaglypts on the cone-shaped front side and an irregular back side. Nearly completely covered by fusion crust. Fusion crust shows a thickened rim 2-10 mm wide around the edge of the back side. On one edge, a fracture surface of approx. 7 × 4 cm exposing the interior is present; another edge shows a fresh fracture surface of approx. 3 × 2 cm, exposing a pre-existing fracture with a surface reminiscent of a shatter cone. These broken edges indicate that about 50 to 100 g are missing and probably were not recovered. Some brownish coloration around metal grains. Some regmaglypts contain traces of brown organic material, probably cattle manure.

Petrography: (B. Hofmann, NMBE, Å. Rosén, UBE/NMBE): Mean chondrule size 0.52±0.28 mm (n=125). Typical size of plagioclase grains is 10-20 μm. Troilite is polycrystalline. Shock stage is S2, some shock veins and shock-blackened areas are visible, no weathering (W0), some rusty coloration around metal grains. Fusion crust melt is invading fractures near the surface.

Geochemistry: Electron microprobe analysis yielded: olivine Fa_17.9±0.5 (Fa_17.4-19.5; n=28), pyroxene Fs_15.7±0.3Wo_1.2±0.2 (Fs_15.4-16.6Wo_0.4-1.9; n=27). Cosmogenic radionuclides: (Å. Rosén, GEMSE): Gamma-spectroscopy performed in September 2016 showed the presence of the following short-lived radionuclides: ⁴⁶Sc, ⁵⁶Co, ⁵⁴Mn, ⁵⁸Co, ⁷Be, ⁵⁷Co, ²²Na, ⁴⁴Ti, ²⁶Al and ⁶⁰Co. Recalculated to 15 March 2016, ²²Na was 65.0(+8.9,-4.8) dpm/kg and ²⁶Al 48.5(+7.8,-3.7) dpm/kg. The ²²Na/²⁶Al activity ratio of 1.3(+0.3,-0.1) is consistent with a fall in March 2016.

Classification: Ordinary chondrite (H5), shock stage S2, no weathering (W0).

Specimens: 25.3 g and two polished thin sections at NMBE. Main mass with Marc Jost.