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Northwest Africa 4518
Basic information Name: Northwest Africa 4518
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 4518
Observed fall: No
Year found: 2003
Country: (Northwest Africa)
Mass:help 167 g
Meteoritical Bulletin:  MB 91  (2007)  Achondrite-ung
Recommended:  Achondrite-ung    [explanation]

This is 1 of 155 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 28 Mar 2007
Writeup from MB 91:

Northwest Africa 4518


Find: 2003

Achondrite (ungrouped)

History: B. Horst purchased the sample in Morocco during 2003.

Physical characteristics: The single piece weighing 167 g is black and covered with shiny black fusion crust. Petrography: (C Lorenz, Vernad; F. Brandstaetter, NHMV) The rock has an achondritic, fine- to medium-grained, equigranular texture displaying triple junctions. It consists of olivine (80 vol%) and pyroxene (20 vol%). Minor phases are Fe,Ni metal (2 vol%); chromite, troilite, Cl-apatite, and merrillite are rare. Pyroxene megacrysts (up to 1 cm in size) containing poikilitic inclusions of olivine, chromite, and Fe,Ni metal also occur in the rock. Troilite and Fe,Ni-rich metal form thin veinlets running through the rock. The olivine grains are replaced by fine-grained intergrowths of pyroxene and troilite along the grain boundaries.

Mineral compositions and geochemistry: Olivine (Fo68.0; Fe/Mn = 35.6, CaO = 0.06, Cr2O3 = 0.04 [both wt%]), pyroxene (En77.7Wo1.2; Fe/Mn = 42, CaO = 0.59, Cr2O3 = 0.12 (both wt%) and En44.7Wo42.3; Fe/Mn = 29.4), Fe,Ni metal (Ni/Co = 9.1; Ni = 5.7 wt%). Oxygen isotopic compositions: (I. A Franchi and R. C Greenwood, OU) By laser fluorination, δ17O = 2.66, δ18O = 5.47, Δ17O = 0.66 (all ‰).

Classification: Achondrite (ungrouped); S1, minor weathering.

Type specimen: A total of 21.3 g and two thin sections are on deposit at Vernad. Horst holds the main mass.

Data from:
  Table 2
  Line 352:
Place of purchase:Morocco
Mass (g):167
Shock stage:S1
Weathering grade:minimal
Fayalite (mol%):32
Classifier:C. Lorenz, Vernad; F. Brandstaetter, NHMV
Type spec mass (g):21.3
Type spec location:Vernad
Main mass:C. Lorenz
Plots: O isotopes:  
   and collections
NHMV: Naturhistorisches Museum, Burgring 7, 1010 Wien, Austria, Austria; Website (institutional address; updated 18 Jan 2019)
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)
Vernad: Vernadsky Institute of Geochemistry and Analytical Chemistry, Russia (institutional address; updated 21 Feb 2016)
Horst: Burkard Horst, Germany (private address)
References: Published in Meteoritical Bulletin, no. 91, MAPS 42, 413-466 (2007)
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     This is 1 of 9776 approved meteorites from (Northwest Africa) (plus 1862 unapproved names)

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