[meteorite-list] Hradec Králové, 2016 Czech Fall Approved

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Wed, 10 May 2017 11:18:07 -0400
Message-ID: <CAKBPJW8zoOS_VBTvcTwe6Nf5KPVW-+vZSDCfYzu25r8=mCGYVg_at_mail.gmail.com>

Hradec Kr?lov?, Czech 2016 fall is approved.

50?18.03?N, 15?43.67?E
Kr?lov?hradeck?, Czech Republic
Confirmed fall: 17 May 2016

Classification: Ordinary chondrite (LL5)

History: (P. Spurn?, CzAS). A slow moving, -11.5 absolute magnitude,
bolide was recorded photographically and photoelectrically by digital
all-sky fireball observatories at three Czech stations of the European
Fireball Network (other stations had bad weather) and by two web
cameras of the Czech Hydrometeorological Institute on May 17, 2016, at
1:04:01.2-7.3 UT. Based on these instrumental data, precise results on
atmospheric trajectory, heliocentric orbit, and fragmentation history
were quickly determined. It was evident that this event terminated
with a multiple meteorite fall and the impact area of possible
meteorite masses was modeled. However, a systematic search was very
complicated because the fall occurred in an agriculturally cultivated
area during the high vegetation season. Nevertheless, the impact area
was announced in the CzAS official press release and the public was
asked for a help with the search. After dedicated search activities of
several teams (including CzAS team) and individual hunters, one
freshly looking meteorite was recovered by a private hunter in the
predicted location for a given mass. It was found in the oil seed
grape field just after the harvest on July 30, 2016 and the finder
informed P. Spurn?(CzAS) about his find in March 2017. The sample was
immediately analyzed by J. Haloda (CzGS).

Physical characteristics: (P. Spurn?, CzAS). Hradec Kralove is a
single, 133 g, slightly wedge-shaped stone measuring approximately 6 ?
3.5 ? 2 cm with bulk density 3.23 g/cm3. About half of its surface is
covered by a thick, black, primary fusion crust, where one side
contains well-developed regmaglypts. The second half of its surface is
covered by a very thin secondary crust signifying a break up of the
meteoroid in the last moment of its ablation phase. Only a few small
rusty spots are visible on its surface. One small 1.1 g fraction was
chipped from this sample and was used for mineralogical/petrological
analyses. Another 22.2 g was cut later and it serves as the repository
mass (CzAS).

Petrography: (J. Haloda, CzGS), The meteorite shows only weakly
defined chondrules; sizes vary from around 0.5 mm to 5 mm. Thin
section shows a complete recrystallization of a fine-grained matrix.
An undulose extinction of olivine and orthopyroxene and presence of
irregular fractures indicate a very weak shock stage (S2).

Geochemistry: Mineral compositions and geochemistry: (J. Haloda,
CzGS), Chondrule relicts consist mostly of olivine (Fa25-33) mean
Fa29.7, Fa PMD 3.5%, n=50; low-Ca pyroxene (Fs21-27Wo0.8-2.4) mean
Fs24.0 Wo1.7, Fs PMD 4.7%, Wo PMD 5.7%, n=50. Feldspar grains <10 mm,
chromite, chlorapatite, troilite, kamacite and taenite are also
present.

Classification: (J. Haloda, CzGS), Ordinary chondrite, LL5 (S2).
Weathering grade W0

Specimens: Type specimen 22.2 g + 0.5 g, CzAS; the main mass (110 g)
is with the finder

Met Bull link - https://www.lpi.usra.edu/meteor/metbull.php?code=65408

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Received on Wed 10 May 2017 11:18:07 AM PDT