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Northwest Africa 5990
Basic information Name: Northwest Africa 5990
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 5990
Observed fall: No
Year found: 2009
Country: Morocco
Mass:help 59 g
Meteoritical Bulletin:  MB 97  (2010)  Shergottite
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 324 approved meteorites (plus 2 unapproved names) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Comments: Approved 9 Dec 2009
Writeup from MB 97:

Northwest Africa 5990


Find (found July 2009, purchased September 2009)

Achondrite (Martian, shergottite)

History: A small stone was found on Hamada du Drâa, Morocco and purchased by Stefan Ralew and Martin Altmann.

Physical characteristics: A single 59 g stone coated on one side by fusion crust showing linear ablation lines. The interior is black, beige, and white with the overall appearance of a terrestrial diabase (Fig. 5).

Petrography: (A. Irving and S. Kuehner, UWS): Medium-grained (up to 1.1 mm) with a subophitic texture, and composed of pyroxene (mostly pigeonite with some subcalcic augite, 35 vol%), plagioclase (35 vol%), and olivine (25 vol%) with accessory chromite, ilmenite, pyrrhotite, Na-Mg-bearing merrillite, and rare magnetite. Shocked plagioclase is in part maskelynite, and in part spherulitic aggregates of birefringent plagioclase blades containing vesicles. None of the minerals exhibit much compositional zoning.

Geochemistry: Olivine (core Fa40.7, rim Fa46.9, FeO⁄MnO = 52.0–53.5), pigeonite (Fs28.3Wo7.8 to Fs33.1Wo12.5, FeO⁄MnO = 27.6–30.0), clinopyroxene (Fs19.9Wo29.9, FeO⁄MnO = 24.1), plagioclase (An64.3-65.2Or0.2–0.1). Oxygen isotopes (D. Rumble, CIW): acid-washed material analyzed by laser fluorination gave, respectively δ18O = 4.15, 4.21; δ17O = 2.41, 2.47; Δ17O = 0.226, 0.253 per mil.

Classification: Achondrite (Martian, shergottite). This specimen is unlike other shergottites in being coarser grained than most (diabasic), and in containing significant amounts of olivine that is not phenocrystic.

Specimens: A total of 11.8 g of type material, two polished thin sections and a polished mount are on deposit at UWS. The remaining material is held by anonymous collectors and institutions.

Fig. 5. Polished face of cut slice of NWA 5990. Scale cube is
1 cm.

Data from:
  Table 1
  Line 355:
Origin or pseudonym:Morocco
Date:July 2009
Mass (g):59
Fayalite (mol%):40.7
Ferrosilite (mol%):28.3-33.1
Wollastonite (mol%):7.8-12.5
Classifier:Irving and Kuehner, UWS
Type spec mass (g):11.8
Type spec location:UWS
Main mass:Anon
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)
CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address)
Ralew: Stefan Ralew, Kunibertstraße 29, 12524 Berlin, Germany; Website (private address)
References: Published in Meteoritical Bulletin, no. 97, MAPS 45, 449-493 (2010)
Find references in NASA ADS:
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Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)


     This is 1 of 2089 approved meteorites from Morocco (plus 32 unapproved names) (plus 1 impact crater)

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