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Northwest Africa 11861
Basic information Name: Northwest Africa 11861
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11861
Observed fall: No
Year found: 2018
Country: (Northwest Africa)
Mass:help 538 g
Meteoritical Bulletin:  MB 107  (2018)  Eucrite-pmict
Recommended:  Eucrite-pmict    [explanation]

This is 1 of 383 approved meteorites classified as Eucrite-pmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 17 Jul 2018
Writeup from MB 107:

Northwest Africa 11861 (NWA 11861)

(Northwest Africa)

Purchased: 2018

Classification: HED achondrite (Eucrite, polymict)

History: A single 538 g stone was found in Morocco prior to 2018. Steve Arnold purchased the stone from a meteorite dealer during the 2018 Tucson Gem and Mineral Show.

Physical characteristics: Stone is irregularly shaped and ~20% is covered by a weathered fusion crust. The weathered exterior is light orangish-gray in color and light gray on the cut face. Numerous mineral and rock clasts can be seen on the cut face.

Petrography: Description and classification (A. Love, App): Sample is a breccia composed of up to 5 mm angular basaltic and cumulate textured eucritic (~13 vol%) and diogenitic (~8 vol%) lithic clasts and related mineral fragments hosted within a fine-grained comminuted matrix. Eucrite clasts have ophitic to subophitic textures and exsolved pyroxenes. Minerals: Chromite, Ilmenite, FeS, Si Polymorph, phosphate.

Geochemistry: (A. Love, App) Eucrite: Low-Ca pyroxene host Fs49.7±7.6 Wo2.5±0.7 (Fs40.7-65.8Wo1.7-4.5, FeO/MnO=27.5-32.3, N=16); pigeonite (Fs42.0±4.4 Wo12.2±6.7 (Fs35.9-48.4Wo8.5-25.7, FeO/MnO=29.0-31.2, N=5); high-Ca pyroxene exsolution lamellae Fs23.73±6.1Wo42.5±1.8 (Fs16.1-33.5Wo39.5-44.2, N=9); plagioclase An85.8±7.4 Or0.6±0.7 (An71.5-94.7, Or0.0-1.6 N=10). Diogenite: Low-Ca pyroxene Fs26.4±3.8 Wo2.4±0.5 (Fs21.1-31.8Wo1.7-3.4, FeO/MnO=27.8-34.7, N=10)

Classification: HED (polymict eucrite breccia). FeO/MnO and Fs compositions of pyroxenes indicate this sample is a HED meteorite composed of a mixture of eucrite and diogenite components.

Specimens: Steve Arnold holds the main mass. Three slices and an endcut totaling 20g 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 2018
Mass (g):538
Shock stage:moderate
Weathering grade:low
Ferrosilite (mol%):49.7±7.6; 42.0±4.4; 23.7±6.1; 26.4±3.8
Wollastonite (mol%):2.5±0.7; 12.2±6.7; 42.5±1.8; 2.4±0.5
Classifier:A. Love, App
Type spec mass (g):20
Type spec location:App
Main mass:Steve Arnold
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)
References: Published in Meteoritical Bulletin, no. 107, MAPS 55, 460-462
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     This is 1 of 8745 approved meteorites from (Northwest Africa) (plus 1880 unapproved names)

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