Chelyabinsk 54°49’N, 61°07’E (approximate centroid)
Chelyabinskaya oblast’, Russia
Fell: 15 Feb 2013; 3:22 UT
Classification: Ordinary chondrite (LL5)
History: At 9:22 a.m. (local time)
on February 15, 2013, a bright fireball was seen by numerous residents
in parts of the Kurgan, Tyumen, Ekaterinburg and Chelyabinsk districts.
Images of the fireball were captured by many video cameras, especially
in Chelyabinsk. Residents of the Chelyabinsk district heard the sound of
a large explosion. The impact wave destroyed many windows in
Chelyabinsk and surrounding cities. Many people were wounded by glass
fragments. A part of the roof and a wall of a zinc plant and a stadium
in Chelyabinsk were also damaged. Numerous (thousands) stones fell as a
shower around Pervomaiskoe, Deputatsky and Yemanzhelinka villages ~40 km
S of Chelyabinsk. The meteorite pieces were recovered and collected out
of snow by local people immediately after the explosion. The snow cover
was about 0.7 m deep. The falling stones formed holes surrounded by
firm snow. Largest stones reached the frozen soil. A stone may have
broken the ice of Chebarkul Lake, located 70 km W of Chelyabinsk. Small
meteorite fragments were found around the 8 m hole in the ice but
divers did not find any stones on the lake bottom.
Physical characteristics: The
meteorite stones and fragments are from <1 g to 1.8 kg in weight and
from a few mm to 10 cm (mainly 3-6 cm) in size. The total mass collected
by local people is certainly >100 kg and perhaps > 500 kg. Fusion
crusted stones are common. The fusion crust is black or brown and
fresh. Broken fragments are rare. The interior of the stones is fresh
but in some pieces there is evidence for weak oxidation of metal grains.
Petrography: (D.D. Badyukov and M.A. Nazarov, Vernad).
The majority (2/3) of the stones are composed of a light-colored
lithology with a typical chondritic texture. Chondrules (~63%) are
readily delineated and set within a fragmental matrix. The mean
chondrule diameter is 0.93 mm. The chondrule glass is devitrified. The
main phases are olivine and orthopyroxene. Olivine shows mosaicism and
planar fractures. Rare grains of augite and clinobronzite are present.
Small and rare feldspar grains show undulatory extinction, planar
deformation features, and are partly isotropic. Troilite (4 vol.%) and
FeNi metal (1.3 vol.%) occur as irregularly shaped grains. Accessory
minerals are chromite, ilmenite, and Cl-apatite. A significant portion
(1/3) of the stones consist of a dark, fine-grained impact melt
containing mineral and chondrule fragments. Feldspar is well developed
and practically isotropic. No high-pressure phases were found in the
impact melt. There are black-colored thin shock veins in both light and
dark lithologies.
Geochemistry: (M.A. Nazarov, N.N. Kononkova, and I.V. Kubrakova, Vernad). Mineral chemistry: Olivine Fa 27.9±0.35, N=22; orthopyroxene Fs22.8±0.8Wo1.30±0.26, N=17; feldspar Ab86;
chromite Fe/Fe+Mg=0.90, Cr/Cr+Al=0.85 (at.%). Major element composition
of the light lithology (XRF, ICP-AS, wt%): Si=18.3, Ti=0.053, Al=1.12,
Cr=0.40, Fe=19.8, Mn=0.26, Ca=1.43, Na=0.74, K=0.11, P=0.10, Ni=1.06,
Co=0.046, S=1.7. Atomic ratios of Zn/Mn × 100=1.3, Al/Mn=8.8. The impact
melt lithology has almost the same composition but it is distinctly
higher in Ni, Zn, Cu, Mo, Cd, W, Re, Pb, Bi (ICP-MS).
Classification: Ordinary chondrite (LL5), shock stage S4, weathering W0.
Specimens: About 400 stones weighing 3.5 kg in total and a few thin sections are in Vernad.
