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Northwest Africa 1863
Basic information Name: Northwest Africa 1863
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 1863
Observed fall: No
Year found: 2019
Country: (Northwest Africa)
Mass:help 1358 g
Recommended:  Eucrite    [explanation]

This is 1 of 560 approved meteorites (plus 1 unapproved name) classified as Eucrite.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 23 Jul 2022
Writeup from MB 111:

Northwest Africa 1863 (NWA 1863)

(Northwest Africa)

Purchased: 2019

Classification: HED achondrite (Eucrite)

History: The meteorite was exported from Morocco for purchase by N. Gessler.

Physical characteristics: A subangular single stone, 60% covered by brown stained matte black grainy non-crazed fusion crust. Broken and cut faces show two textures: a "very light gray N7" matrix with <1 mm grains, and a moderate brown 5YR 4/4 matrix with <4 mm grains.

Petrography: About half of the thin section is a fragmental, but probably monomict, breccia, with typical grain size about 0.10 mm. The other half is essentially unbrecciated, showing a coarse subophitic texture with pyroxene (showing typical eucritic fine-scale exsolution) up to 5 mm, lathy plagioclase up to 2 mm, and silica laths up to 3.5 mm. The grain size of the unbrecciated portion is not consistently that coarse, but the texture is consistently subophitic. The boundary between the brecciated and unbrecciated lithologies is generally quite sharp.

Geochemistry: Mineral-composition data indicate no significant difference between the brecciated and unbrecciated components. Exsolution is coarse enough for EPMA (13 analyses) to resolve low-Ca from high-Ca pyroxene, which cluster near Fs61.2Wo4.2 and Fs31.0Wo40.8, respectively; averaging Fs51.7Wo15.7, with FeO/Mno (wt ratio) = 33.6. Plagioclase (11 analyses) ranges from An74.9 to An90.3 and averages An87.7.

Classification: Eucrite, brecciated, probably monomict

Specimens: Main mass with Gessler, type specimen, including multiple thin sections, at UCLA.

Data from:
  Table 0
  Line 0:
Date:P 2019
Mass (g):1358
Shock stage:S2
Weathering grade:moderate
Ferrosilite (mol%):61.2
Wollastonite (mol%):4.2
Classifier:P. Warren, UCLA
Type spec mass (g):26
Type spec location:UCLA
Main mass:Nick Gessler
Comments: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. 111, in preparation (2022)
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     This is 1 of 8559 approved meteorites from (Northwest Africa) (plus 1896 unapproved names)

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