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Northwest Africa 12542
Basic information Name: Northwest Africa 12542
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12542
Observed fall: No
Year found: 2019
Country: (Northwest Africa)
Mass:help 1082 g
Meteoritical Bulletin:  MB 108  (2020)  Martian (nakhlite)
Recommended:  Martian (nakhlite)    [explanation]

This is 1 of 32 approved meteorites classified as Martian (nakhlite).   [show all]
Search for other: Martian meteorites
Comments: Approved 5 Apr 2019
Writeup from MB 108:

Northwest Africa 12542 (NWA 12542)

(Northwest Africa)

Purchased: 2019 Feb

Classification: Martian meteorite (Nakhlite)

History: Purchased by Ben Hoefnagels in February 2019 from Rachid Chaoui in partnership with a Mauritanian dealer.

Physical characteristics: A single fresh, black stone (1082 g) exhibiting oriented flow lines in remnant fusion crust on one side and portions of two other sides, and with small pits from desert wind ablation on other exterior surfaces.

Petrography: (A. Irving and S. Kuehner, UWS) Cumulate texture. Cumulus phases are larger grains of minimally zoned olivine (up to 2 mm) and chromian titanomagnetite (up to 1 mm) together with twinned, prismatic grains of augite (up to 2 mm long, with thin rims of ferroan augite). Intercumulus regions contain pyrrhotite, K-feldspar, intermediate plagioclase, ferrosilite, ferroan pigeonite, cruciform grains of titanomagnetite and very rare chlorapatite together with K-bearing glass. Secondary chlorophaeite-like material (orange in thin section) is present in some intercumulus regions and also filling fractures in olivine phenocrysts.

Geochemistry: Olivine (Fa65.7-70.2, FeO/MnO = 50-55, N = 4), augite (cores Fs22.8-28.9Wo39.2-38.2, FeO/MnO = 34-37, N = 3; rim Fs45.6Wo40.2, FeO/MnO = 41), ferrosilite (Fs54.9Wo3.1, FeO/MnO = 36), ferroan pigeonite (Fs65.2-66.1Wo6.6-5.8, FeO/MnO = 23-28, N = 2), K-feldspar (Or75.2Ab23.6An1.1), titanomagnetite (Al2O3 = 3.2 wt.%, Cr2O3 = 4.5 wt.%). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave δ17O 3.133, 2.927, 2.950; δ18O 5.463, 5.076, 5.096; Δ17O 0.249, 0.247, 0.259 per mil.

Classification: Nakhlite.

Specimens: 20.6 g including one polished thin section at UWB; remainder with Mr. B. Hoefnagels.

Data from:
  Table 0
  Line 0:
Place of purchase:Mauritania
Date:P 2019 Feb
Mass (g):1082
Class:Martian (nakhlite)
Shock stage:low
Weathering grade:low
Fayalite (mol%):65.7-70.2
Ferrosilite (mol%):22.8-28.9
Wollastonite (mol%):39.2-38.2
Magnetic suscept.:3.87
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):20.6
Type spec location:UWB
Main mass:B. Hoefnagels
Comments:Work name BH200; 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. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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     This is 1 of 9825 approved meteorites from (Northwest Africa) (plus 1851 unapproved names)

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