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Northwest Africa 2990
Basic information Name: Northwest Africa 2990
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 2990
Observed fall: No
Year found: 2007
Country: Western Sahara
Mass:help 363 g
Meteoritical Bulletin:  MB 95  (2009)  Shergottite
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 300 approved meteorites (plus 2 unapproved names) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Comments: Approved 23 Dec 2008
Writeup from MB 95:

Northwest Africa 2990


Find: 2007

Achondrite (Martian, basaltic shergottite)

History and physical characteristics: This single, 363 g stone was recovered in Morocco (Western Sahara) in 2007 and purchased by Adam Aaronson in July 2008. The stone is 65% covered by very fresh, dark fusion crust; areas without fusion crust show a deeply etched surface from wind ablation. A few, thin shock veins are evident on the etched surface.

Petrography (T. Bunch and J. Wittke, NAU and A. Irving, UWS): A very fine-grained basaltic shergottite with small, zoned olivine phenocrysts (mean = 0.27 mm) that are set in a fine-grained groundmass (<0.12 mm) of olivine, twinned tabular pigeonite, augite, maskelynite, chromite, titanomagnetite, ilmenite, FeS, and merrillite. The weathering grade is very low and the shock level is moderate.

Mineral compositions: Olivine phenocrysts are typically zoned from cores of Fa37.6 to rims of Fa47.9 (mean FeO/ MnO = 53), groundmass olivine is Fa45.8–49.7. Maskelynite is An64.3–66.2Or2.7. Pigeonite cores are Fs32.2Wo8.6, rims are Fs41.1Wo10.8 (FeO/MnO = 33). Augite is Fs26Wo28.8 (FeO/ MnO = 29). Ilmenite contains 2.72 wt% MgO and chromite Cr/(Cr+Al) = 0.81–0.85.

Bulk Composition: Powder prepared from a ~1 gram representative interior piece was analyzed by XRF (M. Gellissen and H. Palme, UCologne) and INAA (R. Korotev, WUSL): wt% SiO2 51.08, TiO2 0.62, Al2O3 9.24, FeO 16.42, MgO 8.06, CaO 11.67; ppm Sc 57.4, Cr 830, La 1.46, Sm 1.05, Eu 0.48, Yb 1.22, Lu 0.192. These data signify an enriched type of olivine-phyric shergottite, somewhat like NWA 1068.

Classification: Achondrite (Martian basaltic shergottite).

Type sample: A total of 21.1 g is on deposit at NAU. The main mass holder is Mr. Adam Aaronson.

Writeup from MB 97:
New information on the history of NWA 2990 is that it was purchased from a nomad near the Morocco-
Mauritania border, but the original find location is not known.
Data from:
  Table 2
  Line 38:
Place of purchase:Morocco
Mass (g):363
Fayalite (mol%):37.6-47.9
Ferrosilite (mol%):32.2-41.1
Wollastonite (mol%):8.6-10.8
Classifier:T. Bunch, NAU, and T. Irving, UWS
Type spec mass (g):21.1
Type spec location:NAU
Main mass:Aaronson
   and collections
NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012)
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)
Aaronson: Sahara Overland Ltd., Harhora, Temara, 12000, Morocco (private address; updated 3 Jan 2010)
References: Published in Meteoritical Bulletin, no. 95, MAPS 44, 429-462 (2009)
Published in Meteoritical Bulletin, no. 97, MAPS 45, 449-493 (2010)
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Western Sahara

     This is 1 of 270 approved meteorites from Western Sahara (plus 20 unapproved names)

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