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Chwichiya 002
Basic information Name: Chwichiya 002
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: No
Year found: 2018
Country: Western Sahara
Mass:help 644 g
Classification
  history:
Recommended:  C3.00-ung    [explanation]

This is 1 of 3 approved meteorites classified as C3.00-ung.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 3), and Ungrouped chondrites
Comments: Approved 17 Feb 2020
Writeuphelp
Writeup from MB 109:

Chwichiya 002        27°06’45.02"N, 11°10’25.2"W

Saguia el Hamra, Western Sahara

Find: 2018 Jun 10

Classification: Carbonaceous chondrite (C3.00, ungrouped)

History: Found close to Houza village by Elho Sbiti on June 10, 2018. Bought from Mohamed Elguirad in Guelmim in June and October 2018. More samples bought from Mohamed Elguirah, Habib-Naji Naji and Youssef Ait El Caid in January 2019. Some material bought by Nourddine Azelmat.

Physical characteristics: Fragments and crusted stones, including a 158 g full stone. Cut surface reveals a dark porous interior with chondrules.

Petrography: (J. Gattacceca, CEREGE) Chondrite with well-defined chondrules (average apparent diameter 480±300 μm, n=29) set in an abundant fine-grained iron-rich matrix (74 vol%, by point counting, n=371). Opaques are troilite, magnetite, rare metal (as inclusion in silicates and in the matrix). XRD over a ~1 cm2 area on a polished section (D. Borschnek, CEREGE) does not reveal the presence of hydrous phases (serpentine, tochilinite) typically observed in type 2 chondrites using the same experimental setup. In contrast to type 2 chondrites, IR transmission spectroscopy (L. Bonal, IPAG) on matrix grains only reveal a faint water and Si-O-band (attributable to phyllosilicates), reflecting a very low extent of aqueous alteration. Based on the structural order of the polyaromatic matter assessed by Raman spectroscopy (L. Bonal, IPAG), this meteorite appears to be less heated than the least heated type 3 ordinary chondrite, Semarkona.

Geochemistry: Olivine Fa37.6±16.7, range Fa1.2-46.5 (n=16), Cr2O3 in ferroan olivine 0.39±0.12 wt% (n=11). Low-Ca pyroxene Fs3.1±3.0Wo0.8±0.3 (n=4). Defocussed (10 μm) microprobe totals in the matrix 90.9±1.2% (n=11). Oxygen isotopic composition (J. Gattacceca, C. Sonzogni, CEREGE) from analysis of one acid-washed 1.5 mg aliquot of a powdered 38 mg bulk sample is δ17O=0.42‰, δ18O=8.23‰ , Δ17O=-3.88‰ (linearized, slope 0.5247, analytical uncertainties 0.08‰, 0.12‰, 0.03‰ respectively).

Classification: Carbonaceous chondrite (C3.00-ungrouped). This meteorite is distinct from CM2 chondrites for its larger chondrule size and only incipient aqueous alteration. Type 3.00 is based on the non-detection of phyllosilicates by XRD and microprobe total in the matrix higher than usually measured in type 2 chondrites (see e.g., Ebert et al. 2019, MAPS doi:10.1111/maps.13212), and Raman spectroscopy. Possibly paired with NWA 12957 and NWA 11750 despite having distinct oxygen isotopic composition.

Specimens: Type specimen at CEREGE. Main mass with Jean Redelsperger and Nourddine Azelmat.

Data from:
  MB109
  Table 0
  Line 0:
State/Prov/County:Saguia el Hamra
Place of purchase:Guelmim
Date:2018 Jun 10
Latitude:27°06'45.02"N
Longitude:11°10'25.2"W
Mass (g):644
Pieces:many
Class:C3.00-ung
Weathering grade:moderate
Fayalite (mol%):37.6±16.7 (n=16)
Ferrosilite (mol%):3.1±3.0 (n=4)
Wollastonite (mol%):0.8±0.3
Magnetic suscept.:4.38
Classifier:J. Gattacceca, L. Krämer Ruggiu, CEREGE; L. Bonal, IPAG
Type spec mass (g):39.2
Type spec location:CEREGE
Main mass:Jean Redelsperger, Nourddine Azelmat
Finder:Elho Sbiti
Comments:work name JR058/NA006-SP6; submitted by Jérôme Gattacceca
Plots: O isotopes:  
Institutions
   and collections
CEREGE: CEREGE BP 80 Avenue Philibert, Technopole de l'Arbois 13545 Aix-en-Provence Cedex 4 France, France (institutional address; updated 29 Oct 2018)
IPAG: Institut de Planétologie et d’Astrophysique de Grenoble 414, Rue de la Piscine Domaine Universitaire 38400 St-Martin d’Hères , France (institutional address; updated 1 Aug 2013)
Catalogs:
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
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Photos:
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Allmeteorite.com         
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Geography:

Western Sahara
Coordinates:
     Recommended::   (27° 6' 45"N, 11° 10' 25"W)

Statistics:
     This is 1 of 90 approved meteorites from Saguia el Hamra, Western Sahara
     This is 1 of 220 approved meteorites from Western Sahara (plus 19 unapproved names)
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