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Northwest Africa 13784
Basic information Name: Northwest Africa 13784
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13784
Observed fall: No
Year found: 2020
Country: (Northwest Africa)
Mass:help 290 g
Classification
  history:
Recommended:  CV3-an    [explanation]

This is 1 of 6 approved meteorites classified as CV3-an.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 3), CV chondrites, and CV-CK clan chondrites
Comments: Approved 5 Jun 2021
Writeuphelp
Writeup from MB 110:

Northwest Africa 13784 (NWA 13784)

(Northwest Africa)

Purchased: 2020 Nov

Classification: Carbonaceous chondrite (CV3, anomalous)

History: The meteorite was purchased from a meteorite dealer in Morocco.

Physical characteristics: Dark-grayish rock largely covered with fusion crust.

Petrography: Carbonaceous chondrite composed of well-defined separated type I and II chondrules set in abundant fine-grained matrix dominated by ferrous Ni-free olivine. Chondrules have an apparent mean diameter of 687±579 (N=41), with a maximum diameter of 3.6 mm. Olivine is strongly compositionally zoned in most chondrules and equilibrated in the matrix. Low-Ca pyroxene is also zoned and only present in chondrules, typically concentrated in chondrule rims. Some Ca-pyroxene is present in matrix and chondrules; feldspar was not detected. Opaque phases are troilite and taenite. The section studied contains some small, mostly amoeboid-shaped CAIs predominantly composed of spinel and melilite. Sawn surfaces expose rare up to 4 mm sized CAIs with somewhat diffuse outlines.

Geochemistry: Chondrule olivine: Fa19.6±15.6 (Fa0.7-38.9, Cr2O3=0.09±0.04, n=19); low-Ca pyroxene: Fs4.5±2.3Wo1.2±0.4 (Fs1.7-12.7Wo0.7-2.5, n=21); matrix olivine: Fa38.6±0.4 (Fa37.9-39.5, FeO/MnO=113±9, Cr2O3=0.07±0.04, n=15); Ca-pyroxene: Fs5.2±2.7Wo46.8±1.9 (Fs1.5-7.5Wo42.9-48.7, n=8); oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave: δ18O=0.598, 0.593, 0.634; δ17O=-3.478, -3.868, -3.369; Δ17O=-3.794, -4.181, -3.703 (all per mil)

Classification: Carbonaceous chondrite (CV3, anomalous). CV chondrite based on oxygen isotopic composition and overall petrography. Absence of Cr-bearing magnetite, presence of Ni-free olivine and FeNi metal argue against CK. Matrix dominated by ferrous olivine, chondrule petrography, and dominantly small and rather rare CAIs are unusual for CV chondrites.

Data from:
  MB110
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2020 Nov
Mass (g):289.5
Pieces:1
Class:CV3-an
Shock stage:S2
Weathering grade:low
Fayalite (mol%):28.0±14.8 (N=34)
Ferrosilite (mol%):4.5; 5.2
Wollastonite (mol%):1.2; 46.8
Magnetic suscept.:3.84
Classifier:A. Greshake, MNB
Type spec mass (g):21.8
Type spec location:MNB
Main mass:Hanno Strufe and Andreas Grünemeyer
Comments:Submitted by Ansgar Greshake
Plots: O isotopes:  
Institutions
   and collections
MNB: Museum für Naturkunde, Invalidenstraße 43, D-10115 Berlin, Germany (institutional address; updated 24 Dec 2011)
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
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:
Ansgar Greshake                  
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7727 approved meteorites from (Northwest Africa) (plus 1972 unapproved names)

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