Meteoritical Bulletin: Entry for Northwest Africa 4518

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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: 167 g

Classification
history:

Meteoritical Bulletin:	MB 91	(2007)	Achondrite-ung
Recommended:			Achondrite-ung [explanation]

This is 1 of 131 approved meteorites classified as Achondrite-ung. [show all]
Search for other: Achondrites, Ungrouped achondrites

Comments:

Approved 28 Mar 2007

Writeup

help

Writeup from MB 91:

Northwest Africa 4518

Morocco

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 (Fo_68.0; Fe/Mn = 35.6, CaO = 0.06, Cr₂O₃ = 0.04 [both wt%]), pyroxene (En_77.7Wo_1.2; Fe/Mn = 42, CaO = 0.59, Cr₂O₃ = 0.12 (both wt%) and En_44.7Wo_42.3; 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:
  MB91
  Table 2
  Line 352:

Place of purchase:	Morocco
Date:	2003
Mass (g):	167
Pieces:	1
Class:	Aung
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:

Institutions
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)

Catalogs:

References:

Published in Meteoritical Bulletin, no. 91, MAPS 42, 413-466 (2007)

Find references in NASA ADS:
Find references in Google Scholar:

Geography:

Coordinates:

Unknown.

Statistics:
This is 1 of 9116 approved meteorites from (Northwest Africa) (plus 1873 unapproved names)

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