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Northwest Africa 7904
Basic information Name: Northwest Africa 7904
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 7904
Observed fall: No
Year found: 2012
Country: Morocco
Mass:help 6.33 kg
Meteoritical Bulletin:  MB 102  (2013)  Brachinite
Recommended:  Brachinite    [explanation]

This is 1 of 55 approved meteorites classified as Brachinite.   [show all]
Search for other: Brachinites, Primitive achondrites
Comments: Approved 19 Jun 2013
Writeup from MB 102:

Northwest Africa 7904 (NWA 7904)


Purchased: 2012

Classification: Primitive achondrite (Brachinite)

History: Purchased by Adam Aaronson in 2012.

Physical characteristics: Single stone, rough, oxidized, dark exterior. Broken surface reveals mosaic of shiny, fine-grained crystals.

Petrography: (C. Agee, UNM) Microprobe examination of a polished epoxy mount shows olivine 98%, low-Ca pyroxene 1%, opaques 1%, Fe-metal (oxidized) as films in grain boundaries and crosscutting veinlets. Olivine grain size up to 1 mm. Polygonal texture with numerous equilibrated triple junctions.

Geochemistry: (C. Agee and L. Burkemper, UNM) Olivine Fa 30.0±0.7, Fe/Mn=61±4, n=7; low-Ca pyroxene Fs24.2±0.2Wo2.1±0.0, Fe/Mn=37±1, n=3. (Karen Ziegler, UNM) Oxygen isotope values of 4 acid-washed aliquots of bulk sample, 1.2, 1.8, 1.1, 1.4 mg, gave δ17O = 2.210, 2.634, 2.694, 2.797, δ18O = 4.781, 4.999, 5.166, 5.348, Δ17O = -0.314, -0.005, -0.034, -0.027 (linearized, all permil).

Classification: Primitive achondrite (Brachinite), dunite, with heterogeneous oxygen isotopes, one value within the brachinite array and three values coinciding with the terrestrial fractionation line.

Specimens: 20.5 g including a probe mount on deposit at UNM, Aaronson holds the main mass.

Data from:
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2012
Mass (g):6334
Fayalite (mol%):30.0±0.7
Ferrosilite (mol%):24.2±0.2
Wollastonite (mol%):2.1±0.0
Classifier:C. Agee, UNM
Type spec mass (g):40.5
Type spec location:UNM
Main mass:Aaronson
Comments:Submitted by C. Agee
Plots: O isotopes:  
   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)
Aaronson: Sahara Overland Ltd., Harhora, Temara, 12000, Morocco (private address; updated 3 Jan 2010)
References: Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015
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     This is 1 of 1871 approved meteorites from Morocco (plus 24 unapproved names) (plus 1 impact crater)

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