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New CM2 Carbonaceous Meteorite - Jbilet Winselwan

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#1 Glassthrower

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Posted 21 August 2013 - 11:06 AM

A new carbonaceous CM2 meteorite was approved by Met Soc today -

Name - Jbilet Winselwan
Find coordinates - 26°40.044’N, 11°40.637’W
Find location - Morocco/Western Sahara
Found: 24 May 2013
Classification: Carbonaceous chondrite (CM2)

History: (H. Chennaoui Aoudjehane, M. Aoudjehane, A. Laroussi, A. Bouferra) In early June 2013, A. Bouferra, a meteorite hunter from Smara, reported a new carbonaceous chondrite that had been found close to Smara. Due to its proximity to Smara (7 km), many meteorite hunters visited the area in the summer of 2013.

Physical characteristics: Total mass is estimated about 6 kg, with small and complete pieces between 3 and 10 g, a few medium-sized pieces 10 to 200 g and rare big pieces >200 g. The largest sample is ~900 g. Fresh looking fusion is crust present on many fragments. Some fragments are wind ablated. Some cracks contain secondary, crystalline alteration products. Interior of stones is black and peppered with chondrules.

Petrography: (R. Hewins, MNHNP, L Garvie, ASU). The meteorite contains chondrules and fragments of Types I and II. These include BO-PO, formerly metal-rich, and olivine-pyroxene Type I chondrules. Type II chondrules with forsterite relict grains are present. There are regions packed with chondrule material and coarse PCP, and zones with scattered chondrule material in fine-grained matrix. Chondrule sizes range up to 1.2 mm, though most are around 200 μm. A few CAIs are 800 μm. Powder x-ray diffraction shows a strong 0.7 nm peak for serpentines, a broad but weaker peak around 1.3 nm corresponding to smectites, and a weak broad peak consistent with tochilinite.

Geochemistry: (R. Hewins, MNHNP) Olivine is Fa0.98±0.44 and Fa25-40. Pyroxene is Fs2.6±1.5 and Fs40-61. Rare kamacite with 5.8 wt% Ni is present. (P. Cartigny, IPGP) The oxygen isotopic compositions of two pieces were determined as δ18O 3.811±0.09 and 5.851±0.016, δ17O -2.446±0.040 and -0.601±0.026, respectively. Δ17O values are -4.441 and -3.663, mean -4.052.

Classification: The oxygen isotope compositions, petrography and mineral compositions are all consistent with CM2

Specimens: 17.8 g MNHNP, 17.4 g FSAC provided by L. Labenne, 20 g UNM provided by G. Fujihara, 122 g ASU provided by Farmer. Other collection masses include: Farmer 2.6 kg, Labenne 1.6 kg, T. Jakobowski 512 g, G. Fujihara 358 g, M. Ouzillou 173 g.


Met Bulletin Link - http://www.lpi.usra.....php?code=57788


Best regards and clear skies,

MikeG






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