Meteoritical Bulletin: Entry for Northwest Africa 13673

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Northwest Africa 13673

Basic information

Name: Northwest Africa 13673
This is an OFFICIAL meteorite name.
Abbreviation: NWA 13673
Observed fall: No
Year found: 2020
Country: (Northwest Africa)
Mass: 334 g

Classification
history:

Recommended:

Achondrite (brachinite-like) [explanation]

This is 1 of 4 approved meteorites classified as Achondrite (brachinite-like). [show all]
Search for other: Primitive achondrites, Ungrouped achondrites

Comments:

Approved 19 Mar 2022

Writeup

help

Writeup from MB 111:

Northwest Africa 13673 (NWA 13673)

(Northwest Africa)

Purchased: 2020 Sep

Classification: Achondrite (brachinite-like)

History: Purchased by Habib Naji in September 2020 from a dealer in Laayoune, Morocco.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Protogranular aggregate (mean grainsize ~0.5 mm) of predominantly olivine and low-Ca pyroxene together with subordinate augite plus accessory kamacite, troilite, low-Ti chromite, merrillite, chlorapatite and minor secondary calcite. Small orthopyroxene+kamacite symplectitic intergrowths (up to 60 µm across) occur throughout the specimen. No plagioclase was found.

Geochemistry: Olivine (Fa_23.3-24.2, FeO/MnO = 42-48, N = 5), low-Ca pyroxene (Fs_22.6-23.0Wo_2.0-2.1, FeO/MnO = 31-35, N = 5), augite (Fs_8.9-9.2Wo_44.1-43.9, FeO/MnO = 24-26, N = 2).Oxygen isotopes (K. Ziegler, UNM); analyses of acid-washed subsamples by laser fluorination gave, respectively, δ¹⁷O 2.545, 2.444, 2.535; δ¹⁸O 5.390, 5.200, 5.382; Δ¹⁷O -0.301, -0.302, -0.307 per mil (all data linearized).

Classification: Achondrite (ultramafic, brachinite-like). Brachinite-like achondrites are more magnesian, and have more opx (vs. augite)than brachinites. The olivine composition (Fa and Fe/Mn), and opx/augite abundances also support brachinite-like rather than brachinite. See Day et al. (2012) and Goodrich et al. (2017).

Specimens: 23 g including one polished thin section at UWB; remainder with Mr. H. Naji.

Bibliography:

Day J. M. D., Walker R. J., Ash R. D., Liu Y., Rumble D., Irving A. J., Goodrich C. A., Tait K., McDonough W. F. and Taylor L. A. (2012) Origin of felsic achondrites Graves Nunataks 06128 and 06129, and ultramafic brachinites and brachinite-like achondrites by partial melting of volatile-rich primitive parent bodies. Geochimica et Cosmochimica Acta 81, 94–128. (link)
Goodrich C. A., Kita N. T., Sutton S. R., Wirick S. and Gross J. (2017) The Miller Range 090340 and 090206 meteorites: Identification of new brachinite-like achondrites with implications for the diversity and petrogenesis of the brachinite clan. Meteoritics & Planetary Science 52, 949–978. (link)

Data from:
  MB111
  Table 0
  Line 0:

Place of purchase:	Laayoune
Date:	P 2020 Sep
Mass (g):	334
Pieces:	1
Class:	Achondrite (brachinite-like)
Shock stage:	low
Weathering grade:	low
Fayalite (mol%):	23.2-24.2
Ferrosilite (mol%):	22.6-23.0
Wollastonite (mol%):	2.0-2.1
Classifier:	A. Irving, UWS, and P. Carpenter, WUSL
Type spec mass (g):	23
Type spec location:	UWB
Main mass:	H. Naji
Comments:	Work name DB-1; submitted by A. Irving

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)
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
WUSL: Washington Univ., One Brookings Drive, St. Louis, MO 63130, United States (institutional address; updated 17 Oct 2011)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)

Catalogs:

References:

Published in Meteoritical Bulletin, no. 111, in preparation (2022)

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Geography:

Coordinates:

Unknown.

Statistics:
This is 1 of 9116 approved meteorites from (Northwest Africa) (plus 1873 unapproved names)

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