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Northwest Africa 13685
Basic information Name: Northwest Africa 13685
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13685
Observed fall: No
Year found: 2020
Country: Mauritania
Mass:help 486 g
Classification
  history:
Recommended:  R3-6    [explanation]

This is 1 of 27 approved meteorites classified as R3-6.   [show all]
Search for other: Rumuruti chondrites, Rumuruti chondrites (type 3)
Comments: Approved 13 Feb 2021
Writeuphelp
Writeup from MB 110:

Northwest Africa 13685 (NWA 13685)

Mauritania

Purchased: 2020

Classification: Rumuruti chondrite (R3-6)

History: Two samples weighing a total of 486 g were found prior to 2020. Carlos Muñecas purchased the samples from a dealer in Mauritania in 2020.

Physical characteristics: Samples are irregularly shaped and have a wind-ablated dark brown exterior. A cut face shows the interior is composed of abundant chondrules and sulfides.

Petrography: Description and classification (A. Love, App) Sample is a genomict breccia composed of unequilibrated lithic clasts set within a host of unequilibrated chondrules and fragments in a slightly recrystallized matrix. Sample contains a large amoeboid shaped clast composed of olivine and clinopyroxene and connected networks of secondary plagioclase (avg grainsize 50 µm, n=96). Average chondrule diameter is 353 µm, n=72. Sample contains rare CAIs. Additional minerals are: pentlandite, troilite, chromite, rare orthoclase, plagioclase and apatite.

Geochemistry: Host: Olivine (Fa29.0±15.5 (Fa4.2-44.7), CV%=53 (type 3 material) Fe/Mn=70.8±31.1, n=25); low Ca pyroxene (Fs11.7±7.8Wo1.4±1.5, Fe/Mn=26.6±24.5, n=11); pigeonite (Fs32.0Wo8.9, n=1); high Ca pyroxene (Fs10.3±7.8Wo38.4±2.0, Fe/Mn=31.0±19.4, n=4); equilibrated clast: (Fa37.8±0.3, Fe/Mn=75.5±1.7, n=7); pigeonite (Fs31.2±0.2Wo7.1±0.2, Fe/Mn=43.2±1.2, n=3); high Ca pyroxene (Fs16.9±0.9Wo37.3±1.7, Fe/Mn=39.9±1.0, n=4).

Classification: Rumuruti chondrite (R3-6 breccia C-S3 wi-2). Chondrule diameter, magnetic susceptibility, ubiquitous pentlandite and lack of FeNi metal suggest sample is an R chondrite. Based on unequilibrated compositions of clast and host, sample is an R3.5. Equilibrated mafic silicate compositions, recrystallized texture and grainsize of secondary plagioclase suggests clast is a type-6 R chondrite.

Specimens: Carlos Muñecas holds the 269 g main mass. Several fragments and a sliced end piece weighing a total of 22.73 g and a polished thin section and mount are on deposit at App.

Data from:
  MB110
  Table 0
  Line 0:
Date:P 2020
Mass (g):486
Pieces:2
Class:R3-6
Shock stage:C-S3
Weathering grade:wi-2
Fayalite (mol%):29.0±15.5; 37.8±0.3
Ferrosilite (mol%):11.7±7.8; 10.3±7.8; 16.9±0.9
Wollastonite (mol%):1.4±1.5; 38.4±2.0;37.3±1.7
Magnetic suscept.:3.29
Classifier:A. Love, App
Type spec mass (g):22.73
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:
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Photos:
CreditPhotos
Public domain photographs:
Anthony Love      
Geography:

Mauritania
Coordinates:Unknown.

Statistics:
     This is 1 of 149 approved meteorites from Mauritania (plus 1 unapproved name) (plus 2 impact craters)

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