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Northwest Africa 13640
Basic information Name: Northwest Africa 13640
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13640
Observed fall: No
Year found: 2020
Country: Mauritania
Mass:help 935 g
Classification
  history:
Recommended:  Winonaite    [explanation]

This is 1 of 71 approved meteorites classified as Winonaite.   [show all]
Search for other: Primitive achondrites, Winonaites
Comments: Approved 28 Mar 2021
Writeuphelp
Writeup from MB 110:

Northwest Africa 13640 (NWA 13640)

Mauritania

Purchased: 2020

Classification: Primitive achondrite (Winonaite)

History: A single 935 g sample was found and subsequently purchased by Carlos Muñecas in Mauritania in October 2020.

Physical characteristics: Sample is oriented with dark brown fusion crust coating one side of the flattened disc-shaped stone. The back side of the sample has a large area of exposed FeNi that covers half the surface. The cut face shows the sample is a crystalline mixture of FeNi metal grains and coarse-grained silicates.

Petrography: Description and classification (A. Love, App) escription and classification (A. Love, App) Sample shows poikiloblastic texture composed of (vol%): 0.5-1.0 cm-sized enstatite(49) and diopside(6) oikocrysts enclosing 165 µm (ave. grainsize) olivine chadacrysts(22), anhedral twinned albitic plagioclase(14); FeNi metal(6); troilite(4). Olivine also occurs in lumps of equigranular grains interstitial to oikocrysts. Additional minerals are: graphite (associated with silicates and metals), schreibersite, apatite and possible amphibole.

Geochemistry: (A. Love, App) Olivine (Fa3.1±0.2, Fe/Mn=17.1±1.4, n=27), enstatite (Fs3.6±0.7Wo1.5±0.6, Fe/Mn=12.8±1.6, n=21); diopside (Fs1.4±0.2Wo45.0±0.4, Fe/Mn=10.5±2.2, n=16), oligoclase (An21.3±0.5Or2.7±0.2, n=12).

Classification: Primitive achondrite (Winonaite) Based on abundance of metal and composition of silicates, sample is a winonaite. Grainsize and texture are comparable to Hammadah al Hamra 193.

Specimens: Carlos Muñecas (Expometeoritos) holds the main mass. A 28.70 g slice and a polished thin section are on deposit at App.

Data from:
  MB110
  Table 0
  Line 0:
Place of purchase:Mauritania
Date:P 2020
Mass (g):935
Pieces:1
Class:Winonaite
Shock stage:low
Weathering grade:low
Fayalite (mol%):3.1±0.2
Ferrosilite (mol%):3.6±0.7; 1.4±0.2
Wollastonite (mol%):1.5±0.6; 45.0±0.4
Magnetic suscept.:5.53
Classifier:Anthony Love
Type spec mass (g):28.70
Type spec location:App
Main mass:Carlos Muñecas (Expometeoritos)
Comments:Submitted by Anthony Love
Institutions
   and collections		 App: Department of Geology, 572 Rivers St., Appalachian State University, Boone, NC 28608, United States (institutional address; updated 7 Mar 2013)
Catalogs:
References: Published in Meteoritical Bulletin, no. 110, in preparation (2021)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Public domain photographs:
Anthony Love   
Geography:

Mauritania
Coordinates:Unknown.

Statistics:
     This is 1 of 166 approved meteorites from Mauritania (plus 2 unapproved names) (plus 2 impact craters)

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