[meteorite-list] Met Bull Update : New June 21, 2018 Russia fall (Ozerki) is official.
From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Fri, 20 Jul 2018 21:33:02 -0400
The new Russian fall from 06-21-2018 has been approved,
Text from the Meteoritical Bulletin :
Lipetskaya oblast?, Russia
Confirmed fall: 21 June 2018
Classification: Ordinary chondrite (L6)
History: The first meteorite fragments were recovered based on
analysis of the fireball observed over the Lipetskaya oblast? in
Russia on June 21, 2018, at 01:16:20 UT. The fireball was widely
observed from many places in Russia, including Moscow. The scientists
from UrFU, UHelsinki, and the Finnish Fireball Network formed a
consortium enabling quick prediction and the actual discovery of the
meteorite. Collection of the observational data and trajectory
analysis were done by Esko Lyytinen, Maria Gritsevich, Nikolai
Kruglikov, and Mikhail Larionov. The derived parameters,
characterizing the trajectory were clearly indicative of a number of
meteorite fragments landing on the ground. Using these results, a
comprehensive model of the strewn field providing the expected
locations of fragments was done by Jarmo Moilanen. The area of the
meteorite shower was predicted to be on the line Ozerki ? Zlobino -
Druzhba, Stanovlyansky district, northwest of Yelets town, Lipetskaya
oblast?. The modeling assumed about 100 meteorites (excepting the main
body) with total mass ~7 kg. With the support of these data, a
meteorite recovery campaign was initiated by Victor I. Grokhovsky.
Five samples of the meteorite (1176 g) were recovered during the UrFU
meteorite expedition-2018 (23-27 June 2018; Pastukhovich A.Yu.,
Yakovlev G.A., Petrova E.V. and volunteer Usenkov A.V.) in the
Lipetskaya oblast?. The first sample was found 25 June 2018 by G.A.
Yakovlev (59.85 g). The UrFU finds were near Ozerki village. During
the next few weeks, more meteorite samples (>5500 g) were recovered by
institutional groups (Vernad - GEOKHI RAS, IA RAS, IDG RAS) and
private collectors in the area Ozerki ? Zlobino. The total mass and
number of stones may increase due to additional finds.
Physical characteristics: The meteorites have roughly rounded shapes,
covered by dark fusion crust; the interior is light colored and
contains visible opaque shock veins. The samples are fresh, but halos
of Fe-hydroxides were already present around metal grains. Some
samples contain impact melt.
Petrography: (V.V. Sharygin, SIGM and UrFU, and D.A. Zamyatin, RAS-UB
and UrFU): Petrographic observation of a polished section shows very
rare chondrules in a coarse recrystallized matrix. Most chondrules are
very poorly defined and their apparent sizes vary from 200 ?m to 1 mm.
Only the largest chondrules (up to 4 mm) are clearly delineated. The
PO, POP and BO chondrules are most common and mainly consist of
olivine, plagioclase, low-Ca pyroxene ? chromite and blebs of troilite
and FeNi-metal. Other textural types of chondrules were not observed.
Olivine, low-Ca-pyroxene, plagioclase, FeNi-metal and troilite are the
main minerals in the matrix. Clinopyroxene, chromite, chlorapatite and
merrillite (100-300 ?m) occur locally in the matrix. Plagioclase
grains are larger than 50-100 ?m. Shock features include undulatory
extinction, irregular and planar fractures (three directions) in
olivine and the presence of opaque shock veins. The presence of impact
melt suggests shock stage S5. Grains of FeNi metal (up to 1 mm) are
represented by both individual phases (kamacite, taenite or plessite)
and their intergrowths (kamacite + taenite, kamacite + plessite +
tetrataenite, kamacite + tetrataenite + pentlandite) ? troilite.
Grains of troilite (100-500 ?m) are spongy, fine-grained aggregates of
micrometer-sized individuals (<5 ?m). Some pentlandite grains occur in
such aggregates, especially on contacts with FeNi-metal. Opaque shock
veins (up to 100 ?m in thick) are not very abundant and contain
metal-sulfide intergrowths in fine-grained low-Ca pyroxene matrix. The
thickness of fusion crust is up to 600 ?m. It is highly vesicular and
zoned in texture: the outmost zone is a cryptocrystalline aggregate of
skeletal crystals of zoned olivine and magnetite (up to 5 ?m) and
glass (44-47 wt.% SiO2); the inner zone is represented by larger
skeletal crystals of newly formed olivine + glass + minor magnetite.
Both zones contain rounded relics of initial olivine and chromite and
newly formed Ni-rich metal-sulfide globules (10-20 ?m). Magnetic
susceptibility log ? (? 10-9 m3/kg) = 4.8 (analyst Yakovlev G.A.).
Geochemistry: SEM-EDS-WDS (V. V. Sharygin, SIGM and UrFU) and EMPA-WDS
(D.A. Zamyatin, RAS-UB and UrFU). Olivine Fa25.6?0.3 (N=51), low-Ca
pyroxene Fs21.4?0.2Wo1.6?0.3 (N=44), plagioclase Ab83.5An10.5Or6.0
(N=35), Cr-bearing clinopyroxene En45.8Fs9.0Wo45.2 (Cr2O3 ? 0.8-1.0
wt.%, N=6), chromite Crt82.8Spl12.1 (N=17), chlorapatite, merrillite,
FeNi-metals, troilite and pentlandite. Chlorapatite contains F (up to
0.5 wt.%); Cl ? 5.5, Na2O ? 0.5 wt.% (N=11). Merrillite is poor in FeO
(0.3-0.7 wt.%, N=8). Composition of metal (in wt.%): kamacite (N=32) ?
Fe 93.2?1.4, Ni ? 5.89?1.44, Co ? 0.92?0.13; taenite (N=20) ? Fe
68.6?5.1, Ni 31.0?5.1, Co 0.36?0.09; tetrataenite (N=3) ? Fe 48.5, Ni
51.2, Co 0.16. Composition of sulfides (in wt.%): pentlandite (N=10,
in association with troilite) ? Fe 50.6?0.8, Ni 15.4?1.0, Co
0.15?0.02, Cu 0.61?0.26, S 33.6?0.3; heazlewoodite (N=10, from fusion
crust) ? Fe 2.62?0.46, Ni 71.4?0.8, Co 0.11?0.01, Cu 0.37?0.09, S
Classification: Ordinary chondrite. L6, S5, W0.
Specimens: UrFU - 798.6 g (3 samples: 550.4, 188.3, 59.9 g); Vernad -
603 g (3 samples); SIGM - 31.7 g fragment; RAS-UB - 15 g fragment;
UHelsinki - 15 g fragment.
Met Bull link - https://www.lpi.usra.edu/meteor/metbull.php?code=67709
List of 21st Century Meteorite Falls - http://galactic-stone.com/pages/falls
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