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Northwest Africa 13621
Basic information Name: Northwest Africa 13621
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13621
Observed fall: No
Year found: 2020
Country: Mali
Mass:help 1608 g
Classification
  history:
Recommended:  Lunar (feldsp. breccia)    [explanation]

This is 1 of 220 approved meteorites classified as Lunar (feldsp. breccia).   [show all]
Search for other: Lunar meteorites
Comments: Approved 5 Dec 2020
Writeuphelp
Writeup from MB 109:

Northwest Africa 13621 (NWA 13621)

Mali

Purchased: 2020 Jan-Sep

Classification: Lunar meteorite (feldspathic breccia)

History: Additional stones (total 49 pieces) very similar to the unusual and distinctive specimens classified as Tisserlitine 001, and which were recovered at the same location in Mali, were acquired from several dealers by John Higgins (500 g), Fabien Kuntz (311 g), Dirk Ross (407 g), and an Algerian team represented by David Lehman (390 g). Comparative assessment and analyses of samples from each of these batches of stones were conducted to confirm their pairing with the previous material.

Physical characteristics: Most of the specimens have a flattened slab-like form and all have distinctive medium-brown, "knobby" exterior surfaces coated by desert patina. Interiors of stones are multi-colored (pink, tan, gray) with some darker gray and white clasts and small grains of metal.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Breccia composed of mineral clasts of anorthite, olivine, augite and pigeonite, plus sparse lithic clasts of microcrystalline anorthosite with fine grained mafic phases, are set in a fine grained microvesicular matrix containing accessory altered kamacite, troilite and rare pentlandite together with secondary calcite and barite. Olivine grains have been partially replaced by inhomogeneous phyllosilicate-rich assemblages characterized by systematically low oxide analytical sums (89-94 wt.% ) and deficiency in manganese (yielding elevated FeO/MnO ratios of 119-122).

Geochemistry: Olivine (Fa24.5-40.6, FeO/MnO = 77-98, N = 7), pigeonite (Fs20.6-24.0Wo5.8-6.8, FeO/MnO = 46-50, N = 3), augite (Fs14.1-14.4Wo37.3-41.4, FeO/MnO = 50-54, N = 3), anorthite (An94.6-97.5Or0.0-0.1, N = 3).

Classification: Lunar (feldspathic regolithic breccia, partially hydrothermally-altered). The colors, textures, mineral compositions and distinctive secondary alteration in these specimens establish beyond doubt that they are paired stones to Tisserlitine 001.

Specimens: 22.2 g including a polished endcut and one polished mount at UWB; 25 g plus one polished thin section at PSF; remaining material with Mr. J. Higgins, Kuntz, Mr. D. Ross and Mr. D. Lehman.

Data from:
  MB109
  Table 0
  Line 0:
Place of purchase:Algeria, Morocco
Date:P 2020 Jan-Sep
Mass (g):1608
Pieces:50
Class:Lunar (feldsp. breccia)
Shock stage:low
Weathering grade:moderate
Fayalite (mol%):24.5-40.6
Ferrosilite (mol%):20.6-24.0; 14.1-14.4
Wollastonite (mol%):5.8-6.8; 37.3-41.4
Classifier:A. Irving, UWS, and P. Carpenter, WUSL
Type spec mass (g):22.2
Type spec location:UWB
Main mass:J. Higgins/D. Lehman/F. Kuntz
Comments:Submitted by A. Irving
Institutions
   and collections
PSF: Planetary Studies Foundation,10 Winterwood Lane, Unit B, Galena, Illinois 61036-9283, United States; Website (institutional address; updated 1 Dec 2011)
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
WUSL: Washington Univ., One Brookings Drive, St. Louis, MO 63130, United States (institutional address; updated 17 Oct 2011)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
Kuntz: Fabien Kuntz, France; Website (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
Find references in NASA ADS:
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Geography:

Mali
Coordinates:Unknown.

Statistics:
     This is 1 of 46 approved meteorites from Mali (plus 1 unapproved name)

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