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Northwest Africa 8557
Basic information Name: Northwest Africa 8557
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8557
Observed fall: No
Year found: 2013
Country: (Northwest Africa)
Mass:help 81.6 g
Classification
  history:
Meteoritical Bulletin:  MB 103  (2014)  Eucrite-mmict
Recommended:  Eucrite-mmict    [explanation]

This is 1 of 230 approved meteorites classified as Eucrite-mmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 18 Oct 2014
Writeuphelp
Writeup from MB 103:

Northwest Africa 8557 (NWA 8557)

(Northwest Africa)

Purchased: 2013

Classification: HED achondrite (Eucrite, monomict)

History: Purchased by Brahim Tahiri from a Moroccan hunter and sent to his partner Sean Tutorow for classification, April, 2013.

Physical characteristics: Single stone. Dark irregular weathered exterior. Saw cut reveals numerous coarse light colored feldspathic clasts up to 1 cm, set in a dark-gray matrix.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows fine-grained basaltic texture, grain size ~25-100 μm, also some elongate pyroxene laths 500 × 100 μm, shock melt veins present. Ubiquitous troilite, ilmenite, chromite, and silica. Moderate weathering.

Geochemistry: (C. Agee and N. Muttik, UNM) Low-Ca pyroxene Fs56.6±1.4Wo3.9±1.6, Fe/Mn=35±1, n=15; high-Ca pyroxene Fs26.6±3.1Wo42.3±4.0, Fe/Mn=35±1, n=10; plagioclase An85.9±0.6, n=6; shock melt vein Mg#=39.2, n=5.

Classification: Achondrite (monomict eucrite)

Specimens: 16.5 g including a probe mount on deposit at UNM, Sean Tutorow holds the main mass.

Data from:
  MB103
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2013
Mass (g):81.59
Pieces:1
Class:Eucrite-mmict
Weathering grade:moderate
Ferrosilite (mol%):56.6; 26.6
Wollastonite (mol%):3.9; 42.3
Classifier:C. Agee, UNM
Type spec mass (g):16.5
Type spec location:UNM
Main mass:Sean Tutorow
Comments:Field name G584; submitted by C. Agee, UNM
Institutions
   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)
Catalogs:
References: Published in Meteoritical Bulletin, no. 103, MAPS 52, 1014, May 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12888/full
Find references in NASA ADS:
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Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7101 approved meteorites from (Northwest Africa) (plus 2004 unapproved names)

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