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Northwest Africa 13400
Basic information Name: Northwest Africa 13400
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13400
Observed fall: No
Year found: 2016
Country: (Northwest Africa)
Mass:help 605 g
Classification
  history:
Recommended:  CL3.9    [explanation]

This is 1 of 2 approved meteorites classified as CL3.9.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 3), and CL chondrites
Comments: Approved 5 Sep 2020
Revised 29 Aug 2021: Reclassification
Writeuphelp
Writeup from MB 109:

Northwest Africa 13400 (NWA 13400)

(Northwest Africa)

Purchased: 2016 Dec

Classification: Carbonaceous chondrite (C3, ungrouped)

Petrography: (K. Metzler, IfP) Carbonaceous chondrite, consisting of closely packed, metal-bearing chondrules (apparent size up to 2.8 mm), chondrule fragments, and CAIs (apparent size up to 3.8 mm) with low amounts of interchondrule matrix (17 vol%). The mean apparent chondrule size is 480 µm (n=512).

Geochemistry: Mineral compositions and geochemistry: The mean olivine composition is Fa14.7±1.3 (Fa10.2-16.0, n=30); the mean low-Ca pyroxene composition is Fs6.6±3.7Wo1.0±0.1 (Fs1.2-15.9Wo0.8-1.2, n=20). Oxygen isotopic composition (R. Greenwood, OU): δ17O=-4.017‰, δ18O=-0.021‰, Δ17O=-4.006‰.

Classification: Carbonaceous chondrite (ungrouped). Petrologic type 3.9 based on the percentage mean deviation (PMD) of Fa values (8.8%). Classified as ungrouped due to the low mean Fa and Fs values of olivine and low amount of matrix compared to e.g., CV chondrites. Chondrule size does not fit with either CV, CK or CK chondrites that are the closest groups in terms of oxygen isotopic composition.


Writeup from MB 110:

Northwest Africa 13400 (NWA 13400)

(Northwest Africa)

Find: 2016

Revised classification and description.

Physical characteristics: Carbonaceous chondrite with high chondrule abundance (76 vol%) and low amounts of fine-grained matrix (17 vol%). Composed of irregularly formed Type-I chondrules, few Type-II chondrules, refractory inclusions (CAIs, AOAs), inter-chondrule metal and sulfide grains and matrix. Contains high amounts of (partly terrestrially oxidized) metal (magnetic susceptibility log χ (× 10-9 m3/kg) = 4.78). Fragments of chondrules and refractory inclusions occur, but macroscopically this sample is unbrecciated. It is of shock stage C-S2 and has a weathering grade of W2/3.

Geochemistry: Bulk Ti and Cr isotopic composition: ε50Ti ± 2σ = 2.60±0.07; ε54Cr ± 2σ = 0.70±0.13.

Classification: Due to its characteristically low amount of matrix, highly depleted concentrations of volatile elements, high magnetic susceptibility, low Fa values of nearly equilibrated olivine, and unique position in the ε50Ti-ε54Cr diagram, this sample was reclassified as a CL3.9 chondrite by Metzler et al. (2021).

Bibliography:
  • Metzler K., Hezel D.C., Barosch J., Wölfer E., Schneider J.M., Hellmann J.L., Berndt J., Stracke A., Gattacceca J., Greenwood R.C., Franchi I.A., Burkhardt C., and Kleine T. (2021) The Loongana (CL) group of carbonaceous chondrites. Geochim. Cosmochim. Acta 304, 1–31. (link)
Data from:
  MB109
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2016 Dec
Mass (g):605
Pieces:1
Class:C3-ung
Shock stage:S2
Weathering grade:W2/3
Fayalite (mol%):14.7±1.3 (n=30)
Ferrosilite (mol%):6.6±3.7 (n=20)
Wollastonite (mol%):1.0±0.1
Classifier:K. Metzler, IfP
Type spec mass (g):20
Type spec location:IfP
Main mass:Mirko Graul, Bernau, Germany
Comments:Submitted by K. Metzler, IfP
Plots: O isotopes:  
Institutions
   and collections
IfP: Institut für Planetologie, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany (institutional address; updated 23 Jan 2012)
OU: Planetary and Space Sciences Department of Physical Sciences The Open University Walton Hall Milton Keynes MK7 6AA United Kingdom, United Kingdom (institutional address; updated 8 Dec 2011)
Catalogs:
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
Published in Meteoritical Bulletin, no. 110, in preparation (2021)
Find references in NASA ADS:
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Photos:
CreditPhotos
Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Denis gourgues   
Domjan Svilkovic   
Public domain photographs:
Knut Metzler   
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 8025 approved meteorites from (Northwest Africa) (plus 1951 unapproved names)

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