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Northwest Africa 5718
Basic information Name: Northwest Africa 5718
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 5718
Observed fall: No
Year found: 2006
Country: Algeria
Mass:help 90.5 g
Meteoritical Bulletin:  MB 98  (2010)  Shergottite
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 322 approved meteorites (plus 2 unapproved names) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Comments: Approved 14 May 2010
Writeup from MB 98:

Northwest Africa 5718


Purchased: 2006

Classification: Martian (basaltic shergottite)

History: A fresh, 90.5 g stone was purchased in Erfoud, Morocco, by Mr. Darryl Pitt in 2009. The stone is complete and covered with a shiny, lightly weathered fusion crust.

Petrography: (T. Bunch and J. Wittke, NAU; A. Irving, UWS): This basaltic shergottite is fine to medium-grained (a few prismatic pigeonite grains reach 4.9 mm in length) with ophitic, subophitic, and granular textures. Pigeonite and augite account for 70 vol%, maskelynite (25 vol%), and ulvöspinel, ilmenite, pyrrhotite, and merrillite 5 vol%. Pigeonite and augite are compositionally zoned with mottled extinction, shock lamellae, and kink bands. Small pockets of late-stage K-rich glasses with crystallites of ilmenite, merrillite, pyroxene, and silica are also present. Shock-formed dark, vesicular glass pockets and thin shock melt veins are prominent.

Geochemistry: Pigeonite cores, Fs 30.5 - 39.1 Wo9.6-11.5, rims, Fs 41.8 - 45.7 Wo12-13.2 (FeO/MnO = 32); augite Fs25.4 – 33.4Wo28.3 – 31.1, TiO2 = 1.49 wt % (FeO/MnO = 28). Plagioclase (maskelynite) is zoned with cores of An56.8 Or2.1 to rims of An52.3 Or4.8. Ilmenite MgO = 1.64 wt %. K-rich glasses (wt %) SiO2 = 77.1, Al2O3 = 11.6, K2O = 7.1, Na2O = 2.52, FeO = 1.45. Oxygen isotopes (D. Rumble, CIW): Replicate analyses of acid-washed whole rock samples by laser fluorination gave δ18O = 4.47, 4.29; δ17O = 2.60, 2.50; Δ17O = 0.253, 0.245‰. Bulk rare earth element abundances (ICPMS; C. Herd, UAb): La 3.49, Ce 8.57, Nd 5.92, Sm 2.27, Eu 0.83, Gd 3.63, Dy 4.35, Er 2.53, Yb 2.23, Lu 0.32 (all in ppm).

Classification: Martian (basaltic shergottite). This specimen is an "enriched" shergottite with REE abundances approximately 10 ×f chondrites.

Specimens: 19.4 g is on deposit at NAU. DPitt is the main mass holder.

Data from:
  Table 1
  Line 33:
Place of purchase:Erfoud, Morocco
Date:P 2006
Mass (g):90.5
Ferrosilite (mol%):0.5 - 39.1
Wollastonite (mol%):9.6
Classifier:T. Bunch, J. Wittke, NAU
Type spec mass (g):19.4
Type spec location:NAU
Main mass:DPitt
Comments:Submitted by T. Bunch
Plots: O isotopes:  
   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)
UAb: 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB, T6G 2E3, Canada, Canada; Website (institutional address; updated 17 Oct 2011)
CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address)
DPitt: Darryl Pitt, 225 West 83rd Street, New York, NY 10024, United States; Website (private address)
References: Published in Meteoritical Bulletin, no. 98, MAPS 45, 1530-1551 (2010)
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     This is 1 of 1362 approved meteorites from Algeria (plus 31 unapproved names) (plus 4 impact craters)

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