User:MJCato/Jbilet Winselwan meteorite

= Jbilet Winselwan meteorite = The Jbilet Wiselwan meteorite is a CM-type carbonaceous chondrite found in Western Sahara in 2013. It is notable for having a low shock stage and weathering grade with a large total known weight. Thus, it provides a large amount of relatively pristine material without the cost premium associated with meteorite falls.

Jbilet Winselwan has been identified as a good analog for C-type asteroid sample return missions, such as Hayabusa2. Further study has also indicated that it represents a unique view of C-type asteroid regolith based on micro-scale dehydration textures found throughout the meteorite.

History
The meteorite was reported in early June 2013 by a meteorite hunter from Smara, Western Sahara. The accessibility of the strewn field, being only 7 miles south of Smara, lead to a large number of meteorite hunters visiting the area from the summer of 2013 onward. The majority of specimens range from 3 to 200 grams with a few larger samples occurring, the largest being ~900g. Samples reached the market quickly and the official classification was approved by The Meteoritical Society on the 12th of August, 2013.

Classification and Composition
Jbilet Winselwan was classified as CM-type carbonaceous chondrite at The National Museum of Natural History, France, and The University of Hassan II Casablanca based on its oxygen-isotopic composition, petrography, and mineral compositions. The meteorite contains CAIs and both type I and type II condrules ranging up to 1.2mm with the majority around 200 μm. X-ray diffraction used in classification showed strong peaks for serpentines, broad but weaker peaks for smectites, and a weak broad peak for tochilinite. Major silicate compositions are: Olivine; Fa0.98±0.44 and Fa25-40, and Pyroxene; Fs2.6±1.5 and Fs40-61. Rare kamacite with 5.8 wt% Ni was identified. The oxygen isotopic compositions were measured for two fragments for identification, at δ18O 3.811±0.09 and 5.851±0.016, δ17O -2.446±0.040 and -0.601±0.026, respectively. The isotope values plot well inside the CM chondrite region.

Further Study
As a result of its pristinity and relative ease to obtain, Jbilet Winselwan has been extensively studied for a northwest Africa find. The earliest studies identified its extreme degree of brecciation , showing that it likely represents the the uppermost portion of its parent asteroid; the regolith. This regolith context has been of particular interest, as two missions are currently underway to collect asteroid regolith, Hayabuusa2 and OSIRIS-REx. Jbilet Winselwan has specifically been identified as an analog for Hayabusa2, as the mission is targeting a C-type asteroid, the same class as its likely parent body. In this context, the meteorite was further characterized in its major and minor elements, alteration textures , hydrocarbons , and thermal metamorphism.

The extremely brecciated characteristics of Jbilet Winselwan have also lead people to use it as an indicator of the thermal and hydration history of its parent body. A single thin section will contain multiple lithologies ranging from typically-hydrated CM chondrite material with tightly-packed chondrules to significantly more dehydrated material with few, poorly preserved chondrules. It has been suggested that some Jbilet Winselwan lithologies represent prime examples of post-shock aqueous alteration, including some regions which have formed as a result of cyclical events.