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Northwest Africa 2420
Basic information Name: Northwest Africa 2420
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 2420
Observed fall: No
Year found: 2017
Country: (Northwest Africa)
Mass:help 395 g
Meteoritical Bulletin:  MB 108  (2020)  Lunar
Recommended:  Lunar    [explanation]

This is 1 of 102 approved meteorites classified as Lunar.   [show all]
Search for other: Lunar meteorites
Comments: Approved 7 Nov 2019
Writeup from MB 108:

Northwest Africa 2420 (NWA 2420)

(Northwest Africa)

Purchased: Jan 2017

Classification: Lunar meteorite

History: The meteorite was exported from Morocco to Tucson where it was purchased by N. Gessler.

Physical characteristics: Dark grey matrix with lighter gray to white clasts up to 7 mm.

Petrography: Overall, the sample consists preponderantly of plagioclase, although mafic silicates are comparably abundant in some clasts. The texture is a fine-grained and obviously polymict breccia, but hard to precisely classify. The groundmass is especially fine grained and locally vesicular. But most of the rock consists of diverse lithic and mineral clasts that survived the breccia-forming process. The clasts include earlier-generation impact melt products akin to "crystalline lunar spherules". Glass (i.e., clearly regolithic) spheroids are not found. Several patches of brown, swirly, vesicular glass suggest a possible minor component of regolithic derivation, but the brown color is less diagnostic in a meteoritic find than it would be an Apollo breccia.

Geochemistry: Low-Ca pyroxene (11 analyses) is compositionally diverse, e.g., Fs30Wo11, Fs51Wo9, with average FeO/MnO = 55.9; while 2 augite analyses are Fs20Wo41 and Fs26Wo40. Plagioclase (9 analyses) is An95.4-96.8, average An96.1. The bulk composition, determined by INAA and fused-bead EPMA applied to 2 chips totaling 670 mg, is uncommonly aluminous (31 wt% Al2O3) even for a lunar highland breccia, and also ferroan with bulk Mg/(Mg+Fe) = 57 mol%. For the middle REE Sm, as a representative incompatible element, the sample has 0.9 µg/g, and for the arch-incompatible Th, 0.2 µg/g.

Classification: Lunar highland polymict breccia

Specimens: Main mass with Gessler, type specimen at UCLA.

Data from:
  Table 0
  Line 0:
Place of purchase:Tucson
Date:P Jan 2017
Mass (g):395
Shock stage:S4
Weathering grade:moderate
Ferrosilite (mol%):highly diverse
Wollastonite (mol%):highly diverse
Classifier:P. Warren, UCLA
Type spec mass (g):23
Type spec location:UCLA
Main mass:Nick Gessler
Comments:Gessler's address: 2010 Calgary Lane, Los Angeles, CA 90077; submitted by Paul Warren
   and collections
UCLA: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, United States (institutional address; updated 17 Oct 2011)
Gessler: Nicholas Gessler, 2010 Calgary Lane, Los Angeles, CA 90077, United States (private address; updated 7 Jul 2016)
References: Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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     This is 1 of 9013 approved meteorites from (Northwest Africa) (plus 1869 unapproved names)

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