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Northwest Africa 8781
Basic information Name: Northwest Africa 8781
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8781
Observed fall: No
Year found: 2014
Country: (Northwest Africa)
Mass:help 380 g
Classification
  history:
Recommended:  C-ung    [explanation]

This is 1 of 4 approved meteorites classified as C-ung.   [show all]
Search for other: Carbonaceous chondrites, Ungrouped chondrites
Comments: Approved 23 Sep 2018
Writeuphelp
Writeup from MB 107:

Northwest Africa 8781 (NWA 8781)

(Northwest Africa)

Purchased: 2014 Jul

Classification: Carbonaceous chondrite (Ungrouped)

History: Several black stones found together near Foum Zguid, Morocco, in July 2014 were purchased by Rachid Chaoui and were subsequently sold to Stefan Ralew and Darryl Pitt.

Petrography: (A. Irving and S. Kuehner, UWS, L. Garvie, ASU) Composed of very small chondrules (210±60 µm, N=20) and small mineral fragments in a black, very fine-grained matrix (~50 vol.%). No phyllosilicates were detected by powder-XRD in the matrix. No CAI were observed. Minerals are olivine, orthopyroxene, diopside, stained kamacite and troilite.

Geochemistry: Olivine (Fa1.1-70.7, Cr2O3 in ferroan examples = 0.21-0.40 wt.%, N = 8), orthopyroxene (Fs1.0-7.0Wo1.2-0.4, N = 3), diopside (Fs2.1Wo40.8; Fs0.4Wo48.2). Oxygen isotopes (K. Ziegler, UNM): analyses of five 1-2 mg acid-washed non homogenized subsamples by laser fluorination gave, respectively, δ17O -10.020, -9.832, -6.298, -5.897, -4.490; δ18O -6.085, -5.472, -1.822, -0.895, 1.221; Δ17O -6.807, -6.943, -5.336, -5.424, -5.135 (all per mil). These compositions plot on the CCAM trend, but distinctly below the trend for CO chondrites

Classification: Carbonaceous chondrite (ungrouped). This specimen is not a CV3 chondrite (chondrule size much too small, no CAI), not a CK chondrite (no magnetite), not a CO3 chondrite (oxygen isotopes are different, no CAI), and not a CM chondrite (matrix apparently anhydrous, oxygen isotopes displaced to more 16O-rich compositions). Therefore it seems to be an ungrouped carbonaceous chondrite.

Specimens: 20.1 g including one polished thin section at UWB; 170 g with Kuntz; other samples with Mr. S. Ralew and DPitt.

Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Zagora
Date:P 2014 Jul
Mass (g):380
Pieces:several
Class:C-ung
Shock stage:S2
Weathering grade:low
Fayalite (mol%):1.1-70.7
Ferrosilite (mol%):1.0-7.0
Wollastonite (mol%):1.2-0.4
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):20.1
Type spec location:UWB
Main mass:S. Ralew/D. Pitt
Comments:RC60.2; submitted by A. Irving
Plots: O isotopes:  
Institutions
   and collections
ASU: Center for Meteorite Studies, Arizona State University, Tempe, Arizona 85287-1404, United States; Website (institutional address; updated 14 Jan 2012)
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
DPitt: Darryl Pitt, 225 West 83rd Street, New York, NY 10024, United States; Website (private address)
Kuntz: Fabien Kuntz, France; Website (private address)
Ralew: Stefan Ralew, Kunibertstra├če 29, 12524 Berlin, Germany; Website (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 107, in preparation (2018)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 6551 approved meteorites from (Northwest Africa) (plus 2022 unapproved names)

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