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Northwest Africa 10639
Basic information Name: Northwest Africa 10639
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 10639
Observed fall: No
Year found: 2015
Country: Western Sahara
Mass:help 232 g
Meteoritical Bulletin:  MB 105  (2016)  Eucrite-mmict
Recommended:  Eucrite-mmict    [explanation]

This is 1 of 288 approved meteorites classified as Eucrite-mmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 1 Jun 2016
Writeup from MB 105:

Northwest Africa 10639 (NWA 10639)

Western Sahara

Purchased: 2015 Sept

Classification: HED achondrite (Eucrite, monomict)

History: A single stone of 232 g was found by an anonymous finder in Western Sahara and purchased 2015 in Erfoud by Hichame Mimaghador

Physical characteristics: The main mass is partially covered by a black fusion crust.

Petrography: (V. Moggi Cecchi, G. Pratesi, S. Caporali, UniFi): A thin section displays a monomict brecciated texture consisting of basaltic eucrite clasts and related crystalline debris occuring in a finer-grained matrix. Eucritic clasts are mainly characterized by clinopyroxene, with minor anorthitic plagioclase and orthopyroxene displaying very fine (1-2 μm width) exsolution lamellae. Minor phases include ilmenite, troilite, chromite, and FeNi metal.

Geochemistry: (V. Moggi Cecchi, G. Pratesi, S. Caporali, UniFi) Eucritic clasts: Calcic plagioclase An90.1±1.2Or0.9±0.1, n=6; low-Ca pyroxene (Fs55.2±1.4En42.4±1.2Wo2.4±0.3; n=6; Fe/Mn=37.6±0.3); augite (Fs29.7±1.2En30.6±1.5Wo39.7±1.3; n=7; Fe/Mn=32.8±0.1); pigeonite exsolution lamellae in orthopyroxene (Fs57.7±1.5,En33.8±1.4Wo8.5±0.9; n=8; Fe/Mn = 33.7±0.2). Matrix: low-Ca pyroxene (Fs59.2±1.2En37.6±1.3Wo3.2±0.3; n=7; Fe/Mn=36.7±0.2); Calcic plagioclase An88.7±1.1Or0.5±0.1, n=6; Oxygen isotopes: (I. Franchi, R. Greenwood, OU) δ17O = 1.87‰, δ18O = 4.01‰, Δ17O = -0.21‰

Classification: Eucrite, monomict with high degree of shock and medium degree of weathering.

Specimens: A total of 36.2 g specimen and one thin section is on deposit at MSN-FI. Mimaghador owns the main mass.

Data from:
  Table 0
  Line 0:
Place of purchase:Erfoud
Date:P 2015 Sept
Mass (g):232
Shock stage:high
Weathering grade:medium
Fayalite (mol%):32.7±2.7
Ferrosilite (mol%):59.2±1.2; 57.7±1.5; 29.7±1.2
Wollastonite (mol%):3.2±0.3; 8.5±0.9; 39.7±1.3
Classifier:V. Moggi Cecchi, S. Caporali, G. Pratesi, UniFi
Type spec mass (g):36.2
Type spec location:MSN-FI
Main mass:Mimaghador
Comments:Submitted by Vanni Moggi Cecchi
Plots: O isotopes:  
   and collections
OU: Planetary and Space Sciences Department of Physical Sciences The Open University Walton Hall Milton Keynes MK7 6AA United Kingdom, United Kingdom (institutional address; updated 8 Dec 2011)
MSN-FI: Museo di Storia Naturale “La Specola”, Sez. Mineralogia – Sistema Museale dell'Università degli Studi di Firenze Via Giorgio La Pira, 4 – 50121 Firenze, Italy; Website (institutional address; updated 24 Oct 2022)
UniFi: Università degli Studi di Firenze, P.zza S. Marco, 4 - 50121 Firenze, Italy (institutional address; updated 14 Sep 2013)
References: Published in Meteoritical Bulletin, no. 105, MAPS 52, 2411, September 2017. http://onlinelibrary.wiley.com/doi/10.1111/maps.12944/full
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Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Hichame Mimaghador   

Western Sahara

     This is 1 of 284 approved meteorites from Western Sahara (plus 20 unapproved names)

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