header
  MetSoc Home            Publications            Contacts  
Search the Meteoritical Bulletin Database
Last update: 17 Oct 2021
Search for: Search type: Search limits: Display: Publication:
Names
Text help
Places
Classes
Years
Contains
Starts with
Exact
Sounds like
NonAntarctic
Falls  Non-NWAs
What's new
  in the last:
Limit to approved meteorite names
Search text:  
Northwest Africa 12991
Basic information Name: Northwest Africa 12991
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12991
Observed fall: No
Year found: 2017
Country: Morocco
Mass:help 3.48 kg
Classification
  history:
Meteoritical Bulletin:  MB 108  (2020)  L5
Recommended:  L5    [explanation]

This is 1 of 7227 approved meteorites (plus 4 unapproved names) classified as L5.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 21 Nov 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12991 (NWA 12991)

Morocco

Purchased: 2017 Mar 08

Classification: Ordinary chondrite (L5)

Physical characteristics: Hand specimen shows weathered fusion crust. Cut surface indicates pervasive weathering with oxidised metal and rust staining throughout.

Petrography: Chondrules are dominantly porphyritic with typical size of 800-1000 μm, with one notably large chondrule observed at > 4 mm. Few exhibit discernible edges but most are poorly delineated and chondrule fragments blend in with the recrystallized matrix. Metal grains average at 200 µm in length with modal abundance of ~4 vol%. Both metals and sulphide grains are heavily weathered, and alteration veins are pervasive. Plagioclase grains are dominantly <50 µm in length.

Geochemistry: Mineral composition and geochemistry: All analyses by EPMA. Olivine: Fa25.4±0.6 (N=49). Pyroxene: Fs21.6±0.6En77.0±0.7Wo1.4±0.3 (N=43). Plagioclase: Ab84.1±1.6An10.2±0.6Or5.7±1.8 (N=27). Metal and sulphide analyses had low totals due to weathering.

Data from:
  MB108
  Table 0
  Line 0:
Origin or pseudonym:Near Laayoune
Place of purchase:Morocco
Date:P 2017 Mar 08
Mass (g):3475
Pieces:1
Class:L5
Weathering grade:W4
Fayalite (mol%):25.4±0.6 (N=49)
Ferrosilite (mol%):21.6±0.6 (N=43)
Wollastonite (mol%):1.4±0.3
Classifier:I. S. Mattia, ICL, and N. V. Almeida, NHM
Type spec mass (g):818
Type spec location:NHM
Main mass:Bil Bungay
Comments:Submitted by N. V. Almeida
Institutions
   and collections
NHM: Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom; Website (institutional address; updated 9 Dec 2011)
ICL: Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom (institutional address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
Find references in NASA ADS:
Find references in Google Scholar:
Geography:

Morocco
Coordinates:Unknown.

Statistics:
     This is 1 of 1680 approved meteorites from Morocco (plus 25 unapproved names) (plus 1 impact crater)

Direct link to this page