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Northwest Africa 13581
Basic information Name: Northwest Africa 13581
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13581
Observed fall: No
Year found: 2018
Country: Algeria
Mass:help 6.3 kg
Classification
  history:
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 238 approved meteorites (plus 1 unapproved name) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Comments: Approved 19 Nov 2020
Writeuphelp
Writeup from MB 109:

Northwest Africa 13581 (NWA 13581)

Algeria

Purchased: Dec. 2018

Classification: Martian meteorite (shergottite)

History: Purchased by Bo Zhang in Dec. 2018 from an anonymous dealer.

Physical characteristics: A single cone-shaped stone with fresh fusion crust and flowlines.

Petrography: The specimen is medium- to coarse-grained, exhibiting both poikilitic and non-poikilitic textures. In poikilitic regions, euhedral olivine is enclosed in coarse pyroxene (up to 3 mm). Non-poikilitic regions are composed of cumulate olivine (up to 1 mm), pyroxene and interstitial maskelynite. Other minerals include chromite, ilmenite, phosphate, troilite. Impact melt pockets are present.

Geochemistry: Olivine (Fa46.3-51.2, FeO/MnO=48.8-53.7, n=24); low-Ca pyroxene (Fs28.8-38.6Wo6.0-12.0, FeO/MnO=31.1-38.8, n=16), Ca-rich pyroxene (Fs22.6-30.5Wo21.2-34.9, FeO/MnO=30.2-31.9, n=3); maskelynite (An42.1-48.5Or1.6-2.8, n=11).

Classification: Composition of olivine and pyroxene are more ferrous than typical lherzolitic shergottites, but the texture (including pervasive maskelynization) and chemical signatures (e.g., FeO and MnO of olivine and pyroxene, An and K2O of maskelynite) are compatible with lherzolitic shergottites.

Data from:
  MB109
  Table 0
  Line 0:
Place of purchase:Mali
Date:P Dec. 2018
Mass (g):6300
Pieces:1
Class:Martian (Shergottite)
Fayalite (mol%):48.7±1.0 (n=24)
Ferrosilite (mol%):33.9±2.6 (n=16);25.3±4.5 (n=3)
Wollastonite (mol%):9.4±1.5 (n=16);30.2±7.7 (n=3)
Classifier:Wu Y., PMO
Type spec mass (g):20
Type spec location:PMO
Main mass:Bo Zhang
Comments:Submitted by Hsu W.
Institutions
   and collections
PMO: Purple Mountain Observatory, Nanjing, China (institutional address; updated 16 Dec 2011)
Catalogs:
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
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Photos:
CreditPhotos
Public domain photographs:
Weibiao Hsu      
Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 1042 approved meteorites from Algeria (plus 26 unapproved names) (plus 4 impact craters)

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