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Northwest Africa 4518 | |||||||||||||||||||||||||
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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: ![]() | ||||||||||||||||||||||||
Classification history: |
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![]() |
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 (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: MB91 Table 2 Line 352: |
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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) |
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Catalogs: |
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References: | Published in Meteoritical Bulletin, no. 91, MAPS 42, 413-466 (2007)
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Geography: |
Statistics: This is 1 of 9116 approved meteorites from (Northwest Africa) (plus 1873 unapproved names) |