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Northwest Africa 8173
Basic information Name: Northwest Africa 8173
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8173
Observed fall: No
Year found: 2013
Country: (Northwest Africa)
Mass:help 67.2 g
Meteoritical Bulletin:  MB 103  (2014)  Enst achon
Recommended:  Enst achon    [explanation]

This is 1 of 12 approved meteorites classified as Enst achon.   [show all]
Search for other: Achondrites, Enstatite achondrites, and Enstatite-rich meteorites
Comments: Approved 16 Jun 2014
Writeup from MB 103:

Northwest Africa 8173 (NWA 8173)

Northwest Africa

Purchased: 2013 Oct

Classification: Enstatite achondrite

History: Purchased by Gary Fujihara in October 2013 from a Moroccan dealer.

Physical characteristics: The 67.2 g stone is almost entirely coated by dark fusion crust with stained whitish regions clearly visible. The cut interior consists of white regions with fresh metal and other grayish regions with orange staining from weathering of metal.

Petrography: (A. Irving and S. Kuehner, UWS) The specimen is composed mainly of stubby, prismatic grains of untwinned, pure enstatite with ~20 vol.% stained, holly-leaf shaped grains of Si-bearing kamacite, and accessory alabandite, daubreelite, alkali feldspar, silica polymorph and minor secondary calcite.

Geochemistry: Enstatite (Fs0.0±0.0Wo0.2-0.3, N = 4), metal (Si = 3.6 wt.%, Ni = 6.3 wt.%, Co = 0.4 wt.%, N = 3). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave (all in per mil) δ17O = 2.708, 2.605, 2.400, δ18O = 5.265, 5.013, 4.600, Δ17O = -0.072, -0.042, -0.029 (for a TFL slope of 0.528).

Classification: Enstatite achondrite. This specimen is unlike typical aubrites in several respects: the purity of the enstatite is remarkable (even among other known enstatite-rich meteorites), and the metal is both much more abundant and more Si-rich than in aubrites.

Specimens: 13.6 g and two polished thin sections are at UWB. The remaining material is held by Mr. G. Fujihara.

Data from:
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2013 Oct
Mass (g):67.2
Class:Enst achon
Shock stage:low
Weathering grade:low to m
Ferrosilite (mol%):0.0±0.0
Wollastonite (mol%):0.2-0.3
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):13.6
Type spec location:UWB
Main mass:G. Fujihara
Comments:GF13-12; submitted by A. Irving
Plots: O isotopes:  
   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)
UWB: University of Washington, Burke Museum of Natural History and Culture, Box 353010 Seattle, WA 98195, United States (institutional address; updated 9 Oct 2023)
References: Published in Meteoritical Bulletin, no. 103, MAPS 52, 1014, May 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12888/full
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     This is 1 of 9746 approved meteorites from (Northwest Africa) (plus 1866 unapproved names)

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