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Northwest Africa 4418
Basic information Name: Northwest Africa 4418
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 4418
Observed fall: No
Year found: 2006
Country: (Northwest Africa)
Mass:help 103.8 g
Meteoritical Bulletin:  MB 94  (2008)  Mesosiderite
Recommended:  Mesosiderite    [explanation]

This is 1 of 263 approved meteorites classified as Mesosiderite.   [show all]
Search for other: Mesosiderites, Metal-rich meteorites
Comments: Approved 8 Sep 2008
Writeup from MB 94:

Northwest Africa 4418

Northwest Africa

Find: 2006


History: A complete stone was purchased in Erfoud by a Moroccan dealer for M. Chinellato.

Physical characteristics: The sample is a single stone of 103.8 g, partially covered with black fusion crust.

Petrography: (V. Moggi Cecchi and G. Pratesi, MSP) The meteorite exhibits a heterogeneous texture with large metal areas embedded in a silicate matrix. Metal accounts for 30 vol% of the total surface, with kamacite more abundant than taenite. Schreibersite is accessory. The silicate portion consists of a microbreccia with olivine grains no larger than ~40 μm and clasts of orthopyroxene with very small (1 μm) exsolution lamellae, olivine (up to 200 μm) and plagioclase (up to 100 μm), with minor clinopyroxene. The matrix is formed by orthopyroxene, olivine and minor plagioclase, with orthopyroxene more abundant than plagioclase, thus indicating class B. Textural features indicate type 3.

Geochemistry and mineralogy: Orthopyroxene is Fs29.59En67.32 Wo3.09, FeO/MnO = 26.3–37.0. Clinopyroxene (Fs14.04En43.93 Wo42.03) and exsolution lamellae (Fs21.59En49.84Wo28.57); Plagioclase is An90.6Or0.6. Oxygen isotopes (I. Franchi, R. Greenwood, OU): δ17O = 2.145‰, δ18O = 4.524‰, Δ17O = -0.207‰.

Classification: Mesosiderite, B class; low shock, moderate weathering.

Type specimens: A total of 20.1 g and one thin section are on deposit at MSP. MChin holds the main mass.

Data from:
  Table 2
  Line 19:
State/Prov/County:Northwest Africa
Mass (g):103.8
Ferrosilite (mol%):29.6,14.4
Wollastonite (mol%):3.1,42.0
Classifier:V. Moggi Cecchi, G. Pratesi, Museo di Scienze Planetarie
Type spec mass (g):20.1
Type spec location:MSP
Main mass:MChin
Comments:δ17O = 2.145‰, δ18O = 4.524‰, Δ17O = -0.207‰.
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)
MChin: Matteo Chinellato, Via Triestina, 126/A-30030 Tessera, Venezia, Italy; Website (private address)
References: Published in Meteoritical Bulletin, no. 94, MAPS 43, 1551-1588 (2008)
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Photos from the Encyclopedia of Meteorites:
Don Edwards   

     This is 1 of 9429 approved meteorites from (Northwest Africa) (plus 1876 unapproved names)

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