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Northwest Africa 15915
Basic information Name: Northwest Africa 15915
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 15915
Observed fall: No
Year found: 2023
Country: Algeria
Mass:help 2.84 kg
Recommended:  Achondrite-ung    [explanation]

This is 1 of 140 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 30 Jul 2023
Writeup from MB 112:

Northwest Africa 15915 (NWA 15915)


Purchased: 2023 Feb

Classification: Ungrouped achondrite

History: Purportedly found near Aougrout, Algeria. The largest stone was purchased from the finder by Jaouad Chaoui in October 2022, and subsequently cut and sold in two portions to Jay Piatek and Ben Hoefnagels in February 2023. Three additional stones found at the same location were purchased by Mark Lyon in May 2023 from Jaouad Chaoui.

Physical characteristics: The pale yellowish stones (1359, 808, 650, and 26 g) are partially coated with black fusion crust. The very fresh interiors are predominantly beige in color and somewhat friable.

Petrography: (A. Irving, UWS, and J. Boesenberg, BrownU) Coarse grained protogranular aggregate (mean grainsize ~2 mm) composed predominantly of homogeneous, almost pure end-member diopside (with sparse, very thin exsolution lamellae of enstatite) accompanied by subordinate discrete grains of enstatite (~ 10 vol.%) and accessory daubreelite, alabandite, troilite, minor low-Ni kamacite and secondary Fe oxide. Olivine and plagioclase are absent.

Geochemistry: Diopside (Fs0.0-0.1Wo37.5-43.3, N = 16), enstatite (Fs0.1-0.3Wo0.5-3.2, N = 9). Oxygen isotopes (D. Ibarra, BrownU): analysis of an acid-washed subsample by laser fluorination gave, respectively δ17O 3.369, δ18O 6.470, Δ17O -0.035 per mil (TFL slope value = 0.526).

Classification: Achondrite (ungrouped, Mg-rich diopsidite). These specimens bear some petrologic and isotopic resemblance to Mg-rich websteritic achondrite NWA 13307, but differs in being much richer in clinopyroxene. Although the Δ17O values for both of these Mg-rich specimens are identical, the δ18O value for this specimen is higher by 1 per mil. relative to NWA 13307.

Specimens: 23.8 g including one polished thin section at UWB; portions of the 1359 g main mass are held separately by Mr. J. Piatek (645 g) and Mr. B. Hoefnagels (650 g); other stones of 808 g, 650 g and 26 g are held by Mr. M. Lyon.

Data from:
  Table 0
  Line 0:
Place of purchase:Tucson
Date:P 2023 Feb
Mass (g):2843
Shock stage:low
Weathering grade:low
Ferrosilite (mol%):0.1±0.1; 0.1-0.3
Wollastonite (mol%):42.2-43.3; 0.5-0.7
Classifier:A. Irving, UWS, and J. Boesenberg, BrownU
Type spec mass (g):23.8
Type spec location:UWB
Main mass:J. Piatek/B. Hoefnagels
Comments:Work names JC43 and BH280; submitted by A. Irving
Plots: O isotopes:  
   and collections
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)
BrownU: Joseph Boesenberg Brown University Dept of Earth, Environmental and Planetary Sciences (DEEPS) 324 Brook Street Providence, RI 02912 , United States (institutional address; updated 26 Oct 2023)
References: Published in Meteoritical Bulletin, no. 112, in preparation (2023)
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Photos from the Encyclopedia of Meteorites:
Ben Hoefnagels      


     This is 1 of 1315 approved meteorites from Algeria (plus 30 unapproved names) (plus 4 impact craters)

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