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Northwest Africa 12939
Basic information Name: Northwest Africa 12939
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12939
Observed fall: No
Year found: 2013
Country: Morocco
Mass:help 143 g
Meteoritical Bulletin:  MB 108  (2020)  Ureilite
Recommended:  Ureilite    [explanation]

This is 1 of 630 approved meteorites classified as Ureilite.   [show all]
Search for other: Achondrites, Ureilites
Comments: Approved 23 Dec 2019
Writeup from MB 108:

Northwest Africa 12939 (NWA 12939)


Purchased: 2013

Classification: Ureilite

History: Purchased from A. Aaronson by D. DGregory in Tuscon, Arizona, who provided origin as Morocco. Type specimen is catalogued at the ROM as M58175.

Physical characteristics: The sample is covered by a weathered fusion crust, with one face particularly rusted.

Petrography: The sample is composed of medium to coarse-grained silicates meeting at triple junction boundaries. Modal abundances are approximately 70% olivine, 26% low-Ca pyroxene, and 4% interstitial material, including carbon. Raman analysis confirms the presence of both graphite and diamond. Olivine grains range up to 1.9 mm and exhibit little to no reduction textures and have planar fractures, undulatory extinction, and moderate mosaicism. Low-Ca pyroxene grains range up to 1.1 mm and exhibit twinning and undulatory extinction. Weathering products are common within fractures and along grain boundaries

Geochemistry: Mineral compositions and geochemistry: EPMA quantitative WDS: Olivine cores: Fa13.4±0.3 (N=14), 0.28±0.02 wt% CaO, 0.51±0.03 wt% Cr2O3, and 0.54±0.02 wt% MnO. Pyroxene cores: Fs12.3±0.4Wo4.8±0.4 (N = 13), 2.46 ± 0.14 wt% CaO, 1.02 ± 0.05 wt% Cr2O3, 0.52 ± 0.03 wt% MnO. Oxygen isotopes (K. Ziegler, UNM): analyses of three acid-washed subsamples by laser flourination gave δ17O = 3.191, 3.257, 3.504; δ18O = 8.023, 8.185, 8.666; and Δ17O = -1.045, -1.065, -1.072 (per mil).

Classification: Ureilite

Data from:
  Table 0
  Line 0:
Place of purchase:Tuscon Gem and Mineral Show
Date:P 2013
Mass (g):143.00
Shock stage:moderate
Weathering grade:moderate
Fayalite (mol%):13.4±0.3 (N=14)
Ferrosilite (mol%):12.3±0.3 (N=13)
Wollastonite (mol%):4.8±0.4 (N=13)
Classifier:S. Korchinos, UTorG, ROM
Type spec mass (g):20
Type spec location:ROM
Main mass:DGregory
Comments:Submitted by V. Di Cecco, ROM
Plots: O isotopes:  
   and collections
ROM: Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada (institutional address; updated 18 Oct 2011)
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
Aaronson: Sahara Overland Ltd., Harhora, Temara, 12000, Morocco (private address; updated 3 Jan 2010)
DGregory: David Gregory, 230 First Avenue, Suite 108, St. Thomas, Ontario N5R 4P5, Canada (private address)
UTorG: University of Toronto, Dept. Geology, Earth Sciences Centre, 22 Russell Street Toronto, Ontario, M5S 3B1, Canada (institutional address; updated 31 Jan 2011)
References: Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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     This is 1 of 1974 approved meteorites from Morocco (plus 37 unapproved names) (plus 1 impact crater)

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