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Northwest Africa 11856
Basic information Name: Northwest Africa 11856
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11856
Observed fall: No
Year found: 2017
Country: (Northwest Africa)
Mass:help 137 g
Meteoritical Bulletin:  MB 107  (2018)  Eucrite
Recommended:  Eucrite    [explanation]

This is 1 of 576 approved meteorites (plus 1 unapproved name) classified as Eucrite.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 8 Jul 2018
Writeup from MB 107:

Northwest Africa 11856 (NWA 11856)

(Northwest Africa)

Purchased: 2017

Classification: HED achondrite (Eucrite)

History: A single stone weighing 137 g was found in Morocco prior to 2017. J. Donald Cline and John Sinclair purchased the sample from a meteorite dealer during the 2017 Tucson Gem and Mineral Show.

Physical characteristics: Sample is coated with a patchy, glossy, black, flow-lined fusion crust that covers ~75% of the irregularly shaped stone. Sample contains a number of broad regmaglypts. Areas where fusion crust is absent show a light-colored, fine-grained granular texture.

Petrography: Description and Classification (A. Love, App): Sample is a matrix-supported breccia composed of dominantly of granular mineral fragments and sparse (~8 vol%) small (avg. dia. 1150 μm) angular-subrounded lithic clasts of intergranular to subophitic textured eucrite. Minerals are: birefringent clouded, plagioclase; exsolved pyroxenes; ilmenite; chromite; Fe metal; FeS.

Geochemistry: (A. Love, App) Low-Ca pyroxene host Fs59.4±0.6Wo2.0±0.2 (Fs58.9-61.3Wo1.7-2.3, FeO/MnO=30.2-34.5, N=12); high-Ca pyroxene exsolution lamellae Fs25.8±0.4Wo43.4±0.4 (Fs25.1-26.5Wo42.8-44.0, N=12); plagioclase An82.3±1.4Or0.6±0.2 (An80.7-84.0Or0.4-1.0 N=8).

Classification: HED (eucrite) FeO/MnO and Fs compositions of pyroxenes indicate this sample is a basaltic eucrite. Original igneous textures within clasts are preserved while major element compositions of pyroxenes within sample are equilibrated. Minor element compositions of pyroxenes (Al, Ti, Cr) are less equilibrated. Plagioclase compositions are unequilibrated.

Specimens: PARI holds the main mass. One endcut weighing 20 g and a polished thin section are on deposit at App.

Data from:
  Table 0
  Line 0:
Place of purchase:Tucson Gem and Mineral Show
Date:P 2017
Mass (g):137
Shock stage:low
Weathering grade:low
Ferrosilite (mol%):59.4±0.6; 25.8±0.4
Wollastonite (mol%):2.0±0.2; 43.4±0.4
Classifier:A. Love, App
Type spec mass (g):20.0
Type spec location:App
Main mass:PARI
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)
PARI: Pisgah Astronomical Research Institute 1 Pari Dr Rosman, NC 28772, United States (institutional address; updated 13 Sep 2016)
References: Published in Meteoritical Bulletin, no. 107, MAPS 55, 460-462
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     This is 1 of 9116 approved meteorites from (Northwest Africa) (plus 1873 unapproved names)

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