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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 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:
Ansgar Greshake                  
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 8904 approved meteorites from (Northwest Africa) (plus 1871 unapproved names)

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