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Northwest Africa 13249
Basic information Name: Northwest Africa 13249
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13249
Observed fall: No
Year found: 2019
Country: Libya
Mass:help 4.7 kg
Classification
  history:
Recommended:  C2-ung    [explanation]

This is 1 of 24 approved meteorites classified as C2-ung.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 2), and Ungrouped chondrites
Comments: Approved 11 Nov 2020
Writeuphelp
Writeup from MB 109:

Northwest Africa 13249 (NWA 13249)

Libya

Purchased: March 2019

Classification: Carbonaceous chondrite (C2, ungrouped)

History: Reportedly found 400 km south of Gadamis in the Libya-Algeria border region. Purchased at the market in Gadamis in 2019.

Physical characteristics: Thirty matching stones, fresh fusion crust covers the exterior. Contraction cracks on the surface filled with desert soil are present. Saw cuts reveal numerous small chondrules set in a very dark colored abundant matrix. Friable. Scattered CAIs observed thoughout.

Petrography: (C. Agee, UNM) Microprobe examination shows scattered chondrules, many of which are irregular in shape. There are approximately equal numbers of type I and type II chondrules. Apparent mean chondrule diameter 230±230 μm, n=33. Fine-grained matrix makes up about 70% of this meteorite. Cronstedtite was detected in the matrix. Aluminous diopside and Cr-rich spinel present. Fusion crust is approximately 200 μm thick.

Geochemistry: (C. Agee, UNM) All chondrule olivine Fa24.4±21.6, Fe/Mn=63±44, Cr2O3=0.33±0.15 wt%, n=20; ferroan chondrule olivine Fa40.1±11.5, Fe/Mn=97±12, Cr2O3=0.32±0.11 wt%, n=12; low-Ca pyroxene Fs12.0±13.7Wo1.6±1.0, n=5. Oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave δ18O= -4.759, -6.292, -1.716; δ17O= -8.654, -10.479, -5.673; Δ17O= -6.141, -7.157, -4.767 (linearized, all per mil, TFL slope=0.528).

Classification: Carbonaceous chondrite C2 ungrouped. Type 2 based on the presence of cronstedtite in the matrix. Ungrouped based on the oxygen isotopes plotting near the CO3 field with small chondrules, but the meteorite is petrologic type 2 with abundant matrix. This is not a CM2 or CO3, possibly similar to NWA 5958.

Specimens: 20.1 g on deposit at UNM, DPitt holds the main mass.

Data from:
  MB109
  Table 0
  Line 0:
Place of purchase:Gadamis
Date:P March 2019
Mass (g):4700
Pieces:1
Class:C2-ung
Shock stage:low
Weathering grade:low
Fayalite (mol%):24.4±21.6
Ferrosilite (mol%):12.0±13.7
Wollastonite (mol%):1.6±1.0
Classifier:C. Agee, UNM
Type spec mass (g):20.1
Type spec location:UNM
Main mass:Darryl Pitt
Comments:Field name MVCH486; submitted by C. Agee, UNM
Plots: O isotopes:  
Institutions
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
DPitt: Darryl Pitt, 225 West 83rd Street, New York, NY 10024, United States; Website (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Public domain photographs:
Carl Agee   
Geography:

Libya
Coordinates:Unknown.

Statistics:
     This is 1 of 1519 approved meteorites from Libya (plus 22 unapproved names) (plus 2 impact craters)

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