MetSoc Home            Publications            Contacts  
Search the Meteoritical Bulletin Database
Last update: 3 Jun 2023
Search for: Search type: Search limits: Display: Publication:
Text help
Starts with
Sounds like
Falls  Non-NWAs
What's new
  in the last:
Limit to approved meteorite names
Search text:  
Northwest Africa 7731
Basic information Name: Northwest Africa 7731
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 7731
Observed fall: No
Year found: 2012
Country: Morocco
Mass:help 81 g
Meteoritical Bulletin:  MB 102  (2013)  L3.00
Recommended:  L3.00    [explanation]

This is 1 of 2 approved meteorites classified as L3.00.   [show all]
Search for other: L chondrites, L chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
Comments: Approved 6 Mar 2013
Writeup from MB 102:

Northwest Africa 7731 (NWA 7731)


Purchased: 2012

Classification: Ordinary chondrite (L3.00)

History: Purchased by Adam Bates from a meteorite dealer in Morocco, August 2012.

Physical characteristics: Single stone, black weathered fusion crust, saw-cut reveals many densely packed chondrules of variable size, few fine-grained metal/sulfides.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows numerous unequilibrated chondrules, many to 500 μm, range ~100-2000 μm, abundant fine-grained matrix, kamacite, Fe-oxides, and Fe-sulfide.

Geochemistry: (C. Agee, M. Spilde, L. Burkemper, UNM) Olivine range Fa0.5-18.7, n=31, ferroan olivine Fa10.0±3.4, Fe/Mn=34±17, Cr2O3=0.43±0.11 wt%, range Cr2O3=0.26-0.71 wt%, n=29; low-Ca pyroxene range Fs0.6-13.4, n=31, ferroan low-Ca pyroxene Fs8.0.±7.7Wo0.4±0.3, Fe/Mn=22±18, n=18. Cr-distribution was observed in several ferroan olivines by single scan x-ray imaging, all grains showed uniformly high Cr concentration with no chromite needles or inclusions present. S-distribution was observed in several matrix regions by single scan x-ray imaging, all regions showed high S concentration fairly uniformly distributed in the matrix.

Classification: Ordinary chondrite (L3.00), type 3.00 based on ferroan olivine mean Cr2O3 content and sigma from Grossman and Brearley (2005), by lack of chromite inclusions in ferroan olivine, and by the presence of S-rich matrix.

Specimens: 16.5 g including a probe mount on deposit at UNM, Adam Bates holds the main mass.

Data from:
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2012
Mass (g):81
Fayalite (mol%):0.5-18.7
Ferrosilite (mol%):0.6-13.4
Wollastonite (mol%):0.4±0.3
Classifier:C. Agee, UNM
Type spec mass (g):16.5
Type spec location:UNM
Main mass:Adam Bates
Comments:Submitted by C. Agee
   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)
References: Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015
Find references in NASA ADS:
Find references in Google Scholar:


     This is 1 of 1973 approved meteorites from Morocco (plus 37 unapproved names) (plus 1 impact crater)

Direct link to this page