Meteoritical Bulletin: Entry for Northwest Africa 12445

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Northwest Africa 12445

Basic information

Name: Northwest Africa 12445
This is an OFFICIAL meteorite name.
Abbreviation: NWA 12445
Observed fall: No
Year found: 2018
Country: (Northwest Africa)
Mass: 797 g

Classification
history:

Meteoritical Bulletin:	MB 109	(2020)	Eucrite-an
Recommended:			Eucrite-an [explanation]

This is 1 of 15 approved meteorites classified as Eucrite-an. [show all]
Search for other: Achondrites, Eucrites, and HED achondrites

Comments:

Approved 21 Mar 2020

Writeup

help

Writeup from MB 109:

Northwest Africa 12445 (NWA 12445)

(Northwest Africa)

Purchased: 2018 Aug

Classification: HED achondrite (Eucrite, anomalous)

History: A total of 21 similar stones (total 797 g) were recovered ~70 m apart at a location in Algeria, and were purchased by Mbark Arjdal in August 2018 from an Algerian dealer.

Petrography: (A. Irving and S. Kuehner, UWS) Breccia composed of some lithic eucrite clasts plus a lot of related, angular crystalline debris in a finer grained matrix. Lithic clasts have microgabbroic to subophitic textures. Minerals are exsolved pigeonite (pale orange in thin section), anorthite (exhibiting undulose extinction), silica polymorph, fayalite, ilmenite, troilite and minor Ni-free metal.

Geochemistry: Low-Ca pyroxene host (Fs_67.7±1.6Wo_3.1±1.3, range Fs_66.0-70.6Wo_1.7-5.3, FeO/MnO = 29-31, N = 6; Fs_59.7Wo_2.4, FeO/MnO = 28), high-Ca pyroxene exsolution lamellae (Fs_32.1±2.0Wo_42.8±0.7, range 29.2-34.4Wo_42.0-43.7, FeO/MnO = 30-33, N = 6; Fs_24.7-25.9Wo_44.5-42.9, FeO/MnO = 29-30, N = 2), fayalitic olivine (Fa_73.8±6.5, range Fa_69.3-78.4, FeO/MnO = 46, N = 2), anorthite (An_91.9-93.3Or_0.6-0.3, N = 2).

Classification: Eucrite (breccia, anomalous). The predominance of highly ferroan low-Ca and high-Ca pyroxenes in this specimen is an anomalous feature; these now-exsolved highly ferroan pigeonites are reminiscent of similar pyroxenes in anomalous ferroan eucrite NWA 11729.

Specimens: 38.2 g including one polished thin section at UWB; remainder with Mr. M. Arjdal.

Data from:
  MB109
  Table 0
  Line 0:

Place of purchase:	Algeria
Date:	P 2018 Aug
Mass (g):	797
Pieces:	21
Class:	Eucrite-an
Shock stage:	moderate
Weathering grade:	low
Fayalite (mol%):	73.8±6.5 (N=2)
Ferrosilite (mol%):	67.7±1.6 (n=6)
Wollastonite (mol%):	3.1±1.3
Classifier:	A. Irving and S. Kuehner, UWS
Type spec mass (g):	38.2
Type spec location:	UWB
Main mass:	M. Arjdal
Comments:	Work name Arj18-A10; submitted by A. Irving

Institutions
and collections

UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
UWB: University of Washington, Burke Museum of Natural History and Culture, Box 353010 Seattle, WA 98195, United States (institutional address; updated 9 Oct 2023)

Catalogs:

References:

Published in Meteoritical Bulletin, no. 109, in preparation (2020)

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Photos:

Credit	Photos
Public domain photographs:
A. Irving

Geography:

Coordinates:

Unknown.

Statistics:
This is 1 of 9699 approved meteorites from (Northwest Africa) (plus 1854 unapproved names)

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