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Northwest Africa 13858
Basic information Name: Northwest Africa 13858
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13858
Observed fall: No
Year found: 2020
Country: Algeria
Mass:help 2.44 kg
Recommended:  Mesosiderite    [explanation]

This is 1 of 233 approved meteorites classified as Mesosiderite.   [show all]
Search for other: Mesosiderites, Metal-rich meteorites
Comments: Approved 6 May 2021
Writeup from MB 110:

Northwest Africa 13858 (NWA 13858)


Purchased: 2020

Classification: Mesosiderite

History: (C. Muñecas, Expometeoritos) Sample was found by a nomad in Algeria (coordinates unknown). This meteorite was eventually purchased by Carlos Muñecas (Expometeoritos) from a dealer in Tindouf in 2020.

Physical characteristics: The sample is dark brown and is irregularly shaped with metal grains protruding through the exterior. The interior is a breccia of metal grains and silicates.

Petrography: Description and classification (A. Love, App) Sample is recrystallized breccia composed of (vol%): rounded-irregular-shaped masses of FeNi metal (25) and anhedral silicates (75) which show sutured grain boundaries and avg. grainsize of 516 µm (n=82). Pyroxenes and plagioclase both show poikiloblastic textures and olivine (2 vol%) contain well-developed reaction coronas. Additional minerals are: inverted pigeonite, high Ca pyroxene exsolution lamellae, merrillite, ilmenite, chromite, and both equant and lath shaped silica polymorphs.

Geochemistry: Olivine (Fa28.2±5.5, Fe/Mn=39.4±2.2, n=4); low Ca pyroxene (Fs30.1±4.1Wo3.6±1.2, Fe/Mn=26.3±2.4, n=21); pigeonite (Fs32.3±1.0Wo6.3±1.3, Fe/Mn=26.9±0.9, n=7); high Ca pyroxene (Fs17.2±1.5Wo39.1±1.7, Fe/Mn=20.7±1.2, n=6); plagioclase (An92.4±1.1Or0.3±0.1, n=6).

Classification: Mesosiderite (estimated class A3). Mesosiderite based on abundance of metal and textures of silicates. Class A based on modal abundance of silicates (28 vol% plagioclase, 64 vol% Opx). Metamorphic type 3 based on recrystallized texture with sutured grain boundaries, absence of fine-grained regions, rare pigeonite and well-developed reaction coronas around olivine.

Specimens: C. Muñecas (Expometeoritos) holds the 1007 g main mass. A polished mount, an endcut and several small fragments weighing 24.32g are on deposit at App.

Data from:
  Table 0
  Line 0:
Date:P 2020
Mass (g):2435
Weathering grade:low
Fayalite (mol%):28.2±5.5
Ferrosilite (mol%):30.1±4.1; 17.2±1.5
Wollastonite (mol%):3.6±1.2; 39.1±1.7
Magnetic suscept.:5.59
Classifier:A. Love, App
Type spec mass (g):24.32
Type spec location:App
Main mass:Carlos Muñecas (Expometeoritos)
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. 110, in preparation (2021)
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Public domain photographs:
Anthony Love      


     This is 1 of 1213 approved meteorites from Algeria (plus 29 unapproved names) (plus 4 impact craters)

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