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Northwest Africa 4742
Basic information Name: Northwest Africa 4742
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 4742
Observed fall: No
Year found: 2007
Country: Morocco
Mass:help 376 g
Meteoritical Bulletin:  MB 94  (2008)  Ureilite
Recommended:  Ureilite-pmict    [explanation]

This is 1 of 29 approved meteorites classified as Ureilite-pmict.   [show all]
Search for other: Achondrites, Ureilites
Comments: Approved 17 Apr 2008
Revised 16 Dec 2008: added polymict
Writeup from MB 94:

Northwest Africa 4742


Find: 2001

Achondrite (polymict ureilite)

History: This meteorite was purchased from nomads in Erfoud and acquired by MNHN in 2007.

Physical characteristics: The meteorite comprises a single stone, light tan in color, with altered fusion crust and prominent crystals. It also contains numerous bright crystallites (diamonds). A one-cm splinter on one edge is covered with some thin desert varnish. The total mass of the stone is 376 g.

Petrography: (M. Denise, MNHNP Paris; A. Jambon, O. Boudouma, D. Badia, UPVI; C. Le Guillou and J-N Rouzaud, ENSParis) Classification by EMPA, SEM, and Raman spectroscopy is based on examination of one polished section. The sample contains abundant mm-sized clasts (~30 vol%) of olivine with Fo-rich rims. Within the clasts, reduction rims extend over about 50 μm. The clasts are surrounded by a matrix composed of olivine, low-Ca pyroxene, and subsidiary augite of typically 20–30 μm with a mosaic texture. Numerous mm-sized, interconnected clusters of carbon infill fractures in the matrix. Carbon (~3.5 vol%) is partly amorphous, mostly polycrystalline aggregates of diamond and lonsdaleite (TEM, Raman, XRD) up to several mm and is found in systematic association with oxidized iron sulfide and metal. The thin section also shows rare Ca-carbonate filled veins.

Mineral compositions and geochemistry: Olivine clasts (core) Fo79; Cr2O3 0.6%, CaO 0.3%; FeO/MnO = 44; rims and interstitial olivine up to Fo96. Abundant low-Ca pyroxene: En84Fs15Wo1; FeO/MnO = 42. Minor high-Ca pyroxene variable up to: En45Fs10Wo45; FeO/MnO = 29, Mg# 75 to 81. Remnants of kamacite with 2% Ni are usually altered. Oxygen isotopes (R. Greenwood and I. Franchi, OU) δ17O = 4.71‰, δ18O = 9.61‰, Δ17O = -0.29‰.

Classification: Polymict ureilite

Type specimens: A specimen of 32 g and one polished section are on deposit at UPVI. MNHNP Paris holds the main mass. 10 g Moroccan Imports, Asnières, France

Data from:
  Table 2
  Line 56:
Mass (g):376
Fayalite (mol%):21
Ferrosilite (mol%):16
Wollastonite (mol%):1
Classifier:A. Jambon, O. Boudouma and D. Badia, UPVI
Type spec mass (g):32
Type spec location:UPVI
Main mass:MIA
Plots: O isotopes:  
   and collections
MNHNP: Museum National d'Histoire Naturelle, IMPMC-CP52, 57 rue Cuvier, 75005 Paris, France, France; Website (institutional address)
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)
UPVI: Université Pierre et Marie Curie (Paris VI),Case 110, 4 Place Jussieu, 75005 Paris, France (institutional address; updated 5 Oct 2014)
MNHN: Museum National d'Histoire Naturelle, IMPMC-CP52, 57 rue Cuvier, 75005 Paris, France, France; Website (institutional address)
References: Published in Meteoritical Bulletin, no. 94, MAPS 43, 1551-1588 (2008)
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     This is 1 of 1706 approved meteorites from Morocco (plus 26 unapproved names) (plus 1 impact crater)

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