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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 30 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 Gattacceca J., McCubbin F.M., Grossman J., Bouvier A., Chabot N.L., D'Orazio M., Goodrich C., Greshake A., Gross J., Komatsu M., Miao B., and Schrader D. (2022) The Meteoritical Bulletin, No. 110. Meteorit. Planet. Sci. 1-4
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Photos:
CreditPhotos
Public domain photographs:
Anthony Love      
Geography:

Mauritania
Coordinates:Unknown.

Statistics:
     This is 1 of 184 approved meteorites from Mauritania (plus 1 unapproved name) (plus 2 impact craters)

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