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Northwest Africa 8731
Basic information Name: Northwest Africa 8731
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8731
Observed fall: No
Year found: 2014
Country: (Northwest Africa)
Mass:help 692 g
Meteoritical Bulletin:  MB 104  (2015)  Ureilite
Recommended:  Ureilite    [explanation]

This is 1 of 605 approved meteorites classified as Ureilite.   [show all]
Search for other: Achondrites, Ureilites
Comments: Approved 16 Apr 2015
Writeup from MB 104:

Northwest Africa 8731 (NWA 8731)

(Northwest Africa)

Find: 2014

Classification: Ureilite

History: Recovered in April 2014 near the borders of Mauritania, Western Sahara and Algeria. Purchased in Mauritania in June 2014.

Physical characteristics: A single stone with irregular, dark exterior. A saw cut reveals a fine-grained cumulate texture of pyroxene and olivine grains (0.5-2 mm).

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows approximately 70% pyroxene with exsolution lamellae (inverted pigeonite) and 25% olivine with very fine iron-reduction zonation, accessory Fe-Ni metal and iron oxide. There is graphite phase on grain boundaries and triple junctions.

Geochemistry: (C. Agee and N. Muttik, UNM). Olivine Fa5.7±0.7, Fe/Mn=11±1, Cr2O3=0.60±0.02 CaO=0.32±0.02 (wt%), n=14; low-Ca pyroxene Fs5.6±0.7Wo4.9±0.1, Fe/Mn=8±1, n=4; augite Fs3.2±0.1Wo36.9±0.3, Fe/Mn=6±0, n=6.

Classification: Achondrite (augite-bearing ureilite). Moderate weathering grade, low shock stage.

Specimens: 21.3 g including a probe mount on deposit at UNM, DPitt holds the main mass.

Data from:
  Table 0
  Line 0:
Place of purchase:Mauritania
Mass (g):691.7
Shock stage:low
Weathering grade:moderate
Fayalite (mol%):5.7±0.7
Ferrosilite (mol%):5.6±0.7
Wollastonite (mol%):4.9±0.1
Classifier:C. Agee, UNM
Type spec mass (g):21.3
Type spec location:UNM
Main mass:Darryl Pitt
Comments:Field name MAC 84; submitted by C. Agee, UNM
   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)
DPitt: Darryl Pitt, 225 West 83rd Street, New York, NY 10024, United States; Website (private address)
References: Published in Meteoritical Bulletin, no. 104, MAPS 52, 2284, Octover 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12930/full
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     This is 1 of 8509 approved meteorites from (Northwest Africa) (plus 1899 unapproved names)

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