[meteorite-list] Oudiyat Sbaa, EH5 fall is now official.

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Sun, 21 May 2017 21:40:26 -0400
Message-ID: <CAKBPJW8j3kjrZt6uFQ6joNp8-rf9bo5Zy7vyKVo=1CB9XjajZA_at_mail.gmail.com>

Oudiyat Sbaa meteorite fall is official. This EH5 chondrite fell over
Morocco on November 16, 2016.

Oudiyat Sbaa 25.546?N, 12.418?W
Western Sahara/Morocco
Confirmed fall: 2016 Nov 18

Classification: Enstatite chondrite (EH5)

History: On November 18, 2016, at 4:40 pm local time, a bright
fireball was witnessed traveling in a southerly direction by many
observers in Morocco over an area extending from Tiznit to Guelmim,
Tan Tan and Smara. Sonic booms were heard by Mbarek Bouilid, Aitoussi
Redwan and three camel shepherds of the Aitboussoula family (who
thought that perhaps the sound was caused by explosion of a mine
trodden on by a camel). A search for fallen stones was begun, and on
November 23 another shepherd (Bachir Alamine) found three black
fusion-crusted stones on light brown sandy soil near Oudiyat Sbaa.

Physical characteristics: The stones are completely coated in thin,
black fusion crust. The fresh interiors are overall medium gray in
color with abundant shiny grains of metal and sulfides. When first
found the stones emitted a sulfurous odor.

Petrography: (A. Irving and S. Kuehner, UWS) Some well-formed
chondrules (apparent diameter 300?100 ?m) are present within a
recrystallized matrix containing abundant metal and sulfides. Apart
from dominant enstatite, the specimen contains alkali feldspar,
Si-bearing kamacite, niningerite, oldhamite, Cr-bearing troilite and
schreibersite. A spherical crystalline object (apparent diameter 1.1
mm) observed in one thin section is composed predominantly of
fluororichterite associated with a silica polymorph, enstatite and
sulfides.

Geochemistry: Enstatite (Fs0.4-0.6Wo0.1-0.3, N = 3), alkali feldspar
(Ab88.7-93.1An1.1-0.9Or10.2-6.0, N = 2), metal (Ni 6.2-6.3 wt.%, Co
0.4 wt.%, Si 3.3 wt.%, N = 2). Cosmogenic radionuclides: (?. Ros?n,
UBE/NMBE, GeMSE): Gamma-spectroscopy performed in February 2017 showed
the presence of the following cosmogenic radionuclides: 46Sc, 56Co,
54Mn, 58Co, 7Be, 48V, 51Cr, 57Co, 22Na, 44Ti and 26Al. Recalculated to
18 November 2016 and assuming average EH chondrite density and
composition, 48V was 43.0 (+7.8,-5.2), 22Na was 60.8 (+8.1,-4.6)
dpm/kg and 26Al 53.6 (+7.9,-3.4) dpm/kg. The 22Na/26Al activity ratio
of 1.1 (+0.2,-0.1) and detected activity of 48V (t1/2=16 d) are
consistent with a fall in November 2016. Magnetic susceptibility log ?
(? 10-9 m3/kg) = 5.74.

Classification: Enstatite chondrite (EH5).

Specimens: 173.7 g including one polished thin section and a polished
thick section at UWB; 17.3 g plus one polished thin section at NMBE;
remainder with DPitt.

Met Bull link - https://www.lpi.usra.edu/meteor/metbull.php?code=65515

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Received on Sun 21 May 2017 09:40:26 PM PDT