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Northwest Africa 4537
Basic information Name: Northwest Africa 4537
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 4537
Observed fall: No
Year found: 2005
Country: Morocco
Mass:help 261 g
Meteoritical Bulletin:  MB 94  (2008)  Aubrite
Recommended:  Aubrite    [explanation]

This is 1 of 83 approved meteorites classified as Aubrite.   [show all]
Search for other: Achondrites, Aubrites, Enstatite achondrites, and Enstatite-rich meteorites
Comments: Approved 8 Sep 2008
Writeup from MB 94:

Northwest Africa 4537


Find: 2005

Achondrite (aubrite)

History: Purchased in 2006, by Matteo Chinellato, from a Moroccan dealer in Erfoud.

Physical characteristics: A single green complete stone lacking fusion crust with a total weight of 261 g and displaying minute spots of yellow-orange staining and larger dark brown on the exterior.

Petrography: (V. Moggi Cecchi and G. Pratesi, MSP) The thin section displays a uniform very fine-grained equigranular texture consisting of bladed grains of enstatite with sporadic clasts of enstatite (up to 0.7 mm across). The grain size is variable from 80 to 210 μm in width and up to 270 μm in length. Relatively few enstatite grains exhibit lamellar twinning. Other silicate phases include plagioclase, blades of daubreelite up to 50 μm in width, and rare troilite, Fe,Ni metal and schreibersite grains rounded. Minor barite and calcite are present, probably due to terrestrial weathering.

Geochemistry: Pyroxene (En98.5Wo1.5; Al2O3 = 0.19 wt%), plagioclase (An14.3Or4.1). Oxygen isotopes (R. Greenwood, I. Franchi, OU) δ17O = 2.650‰; δ18O = 5.021‰; Δ17O = +0.039‰.

Classification: Achondrite (aubrite). Minor weathering effects on troilite, and minor yellow-orange staining on exterior surface.

Type specimen: A total of 136 g, one polished thin section and one block are on deposit at MSP; the Museo di Storia Naturale dell’Università di Firenze holds the remaining 125 g mass.

Data from:
  Table 2
  Line 35:
Mass (g):261
Ferrosilite (mol%):1.5
Wollastonite (mol%):1.5
Classifier:V. Moggi Cecchi, G. Pratesi, Museo di Scienze Planetarie
Type spec mass (g):136
Type spec location:MSP
Main mass:MSP
Comments:δ18O = 5.021‰; δ17O =2.650‰; Δ17O = +0.039‰.
Plots: O isotopes:  
   and collections
MSP: Museo di Scienze Planetarie, Via Galcianese 20/H, 59100 Prato, Italy, Italy; Website (institutional address; updated 22 Oct 2022)
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)
References: Published in Meteoritical Bulletin, no. 94, MAPS 43, 1551-1588 (2008)
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     This is 1 of 2094 approved meteorites from Morocco (plus 32 unapproved names) (plus 1 impact crater)

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