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Northwest Africa 12531
Basic information Name: Northwest Africa 12531
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12531
Observed fall: No
Year found: 2018
Country: (Northwest Africa)
Mass:help 530 g
Meteoritical Bulletin:  MB 108  (2020)  Eucrite-melt breccia
Recommended:  Eucrite-melt breccia    [explanation]

This is 1 of 57 approved meteorites classified as Eucrite-melt breccia.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 31 Aug 2019
Writeup from MB 108:

Northwest Africa 12531 (NWA 12531)

(Northwest Africa)

Purchased: 2018

Classification: HED achondrite (Eucrite, melt breccia)

History: Twenty-three identical stones with a total known weight of 530 g were found in Western Sahara in 2018. The samples were purchased from a prospector in Rissani in 2018 and subsequently obtained by David DGregory during the 2019 Tucson Gem and Mineral Show.

Physical characteristics: Samples are irregularly shaped, lack fusion crust and are dark gray with light-colored clasts. Vesicles are visible on surface. Some samples appear to be composed mostly of melt and contain higher density of vesicles.

Petrography: Description and classification (A. Love, App): A representative 23 g individual displaying the brecciated and vesicular melt textures was selected as the type specimen for description and analysis. The sample is a breccia composed of rounded clasts of coarse-grained (1.2 mm pyroxenes and 1 mm plagioclase), basaltic textured eucrite and related mineral debris set within a vesicular, quench-textured melt matrix. Clasts contain lithic fragments with embayed, exsolved pyroxenes surrounded by vesicular plagioclase. Additional minerals are: Si polymorphs, rare baddeleyite, phosphate, zircon, Ti-poor (3 wt% TiO2) and rich (<18 wt% TiO2) chromite which is sometimes inter-grown with ilmenite, troilite and Fe metal.

Geochemistry: (A. Love, App) Basaltic eucrite clasts: low Ca pyroxene Fs55.2±5.3Wo2.5±1.2 (Fs48.8-63.6Wo1.9-6.3), Fe/Mn=29.6, Mg#35.0-48.6, n=12; high Ca pyroxene Fs22.6±2.8Wo44.1±0.6, N=12; Plagioclase An92.1±0.7Or0.2±0.0, N=6. Melt Matrix: Pigeonite Fs64.4±6.2Wo18.6±3.8, Fe/Mn=34.7, Mg#=8.7-38.2, N=6.

Classification: Eucrite-melt breccia.

Specimens: David DGregory holds the remaining 22 individuals that comprise the mass of this meteorite. One partially cut stone weighing 21.15 g and a polished thin section comprise the type specimen and are on deposit at App.

Data from:
  Table 0
  Line 0:
Place of purchase:Rissani
Date:P 2018
Mass (g):530
Class:Eucrite-melt breccia
Shock stage:M-S5
Weathering grade:low
Ferrosilite (mol%):55.2±5.3; 22.6±2.8; 64.4±6.2
Wollastonite (mol%):2.5±1.2; 44.1±0.6; 18.6±3.8
Classifier:A. Love, App
Type spec mass (g):21.15
Type spec location:App
Main mass:Aaronson
Comments:Submitted by Anthony Love
   and collections
App: Department of Geology, 572 Rivers St., Appalachian State University, Boone, NC 28608, United States (institutional address; updated 7 Mar 2013)
Aaronson: Sahara Overland Ltd., Harhora, Temara, 12000, Morocco (private address; updated 3 Jan 2010)
DGregory: David Gregory, 230 First Avenue, Suite 108, St. Thomas, Ontario N5R 4P5, Canada (private address)
References: Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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     This is 1 of 8138 approved meteorites from (Northwest Africa) (plus 1941 unapproved names)

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