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Northwest Africa 12696
Basic information Name: Northwest Africa 12696
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12696
Observed fall: No
Year found: 2017
Country: Algeria
Mass:help 20 kg
Classification
  history:
Recommended:  Eucrite-melt breccia    [explanation]

This is 1 of 24 approved meteorites classified as Eucrite-melt breccia.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 27 Jul 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12696 (NWA 12696)

Algeria

Purchased: 2017

Classification: HED achondrite (Eucrite, melt breccia)

History: Reportedly found in Algeria. Approximately 200 identically appearing pieces were purchased during a period commencing October 2017 from dealers in Mauritania and Morocco through February 2018, after which it was sold at the Tucson Show by numerous meteorite dealers.

Physical characteristics: Saw cut reveals domains of vesiculated, dark gray, shock melt grading into a fragmental breccia of light-colored basaltic clasts.

Petrography: (C. Agee, UNM) Microprobe examination shows basaltic clasts with approximately 60% pyroxene and 35% plagioclase grains most in the range 200-500 μm. Many pyroxene grains have exsolution lamellae. Shock melt veins and pockets are found throughout, many containing fragmental pyroxene and plagioclase grains. Ubiquitous minor chromite, troilite, and ilmenite were observed.

Geochemistry: (C. Agee, UNM) Low-Ca pyroxene Fs61.9±1.4Wo2.5±0.8, Fe/Mn=31±1, n=8; high-Ca pyroxene Fs30.6±5.9Wo39.7±5.8, Fe/Mn=32±1, n=4; plagioclase An88.4±2.1, n=6.

Classification: Eucrite-melt breccia, eucrite clasts are consistent with type 6 (Takeda and Graham, 1991) showing clear compositional separation of low and high calcium pyroxenes. Possibly paired with NWA 12342.

Specimens: 22.7 g on deposit at UNM, DPitt holds the main mass.

Bibliography:
  • H. Takeda and A.L. Graham (1991) Degree of equilibration of eucritic pyroxenes and thermal metamorphism of the earliest planetary crust. Meteoritics 26 129-134. (link)
Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:Mauritania,Morocco,Tucson
Date:P 2017
Mass (g):20000
Pieces:200
Class:Eucrite-melt breccia
Shock stage:high
Weathering grade:moderate
Ferrosilite (mol%):61.9±1.4, 30.6±5.9
Wollastonite (mol%):2.5±0.8, 39.7±5.8
Classifier:C. Agee, UNM
Type spec mass (g):22.7
Type spec location:UNM
Main mass:DPitt
Comments:Field name MVCH313; submitted by C. Agee, UNM
Institutions
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
DPitt: Darryl Pitt, 225 West 83rd Street, New York, NY 10024, United States; Website (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 108, in preparation (2019)
Find references in NASA ADS:
Find references in Google Scholar:
Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 970 approved meteorites from Algeria (plus 26 unapproved names) (plus 4 impact craters)

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