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Northwest Africa 11961
Basic information Name: Northwest Africa 11961
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11961
Observed fall: No
Year found: 2018
Country: (Northwest Africa)
Mass:help 324 g
Meteoritical Bulletin:  MB 108  (2020)  C3-ung
Recommended:  C3-ung    [explanation]

This is 1 of 26 approved meteorites classified as C3-ung.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 3), and Ungrouped chondrites
Comments: Approved 5 Jan 2019
Writeup from MB 108:

Northwest Africa 11961 (NWA 11961)

(Northwest Africa)

Purchased: 2018 Jan

Classification: Carbonaceous chondrite (C3, ungrouped)

History: Purchased by Greg Hupe in January 2018 from a Moroccan dealer at the Tucson Gem and Mineral Show.

Physical characteristics: Two identical brownish stones (total weight 324.3 g). Cut interior surfaces reveal light brown chondrules in a dark brown matrix containing fresh metal.

Petrography: (A. Irving and S. Kuehner, UWS; L. Garvie, ASU) Unequilibrated specimen. Composed of fairly closely packed, well formed granular chondrules (apparent diameter 840±500 µm, some with metal-rich rims) set in a fine-grained matrix (~15 vol.%, deep red-brown in thin section) containing minor secondary calcite. Orthopyroxene is rare relative to clinopyroxene, and anorthite is present both in chondrules and matrix; accessory phases include kamacite (~2 vol%) and troilite. Troilite is the only sulfide. No magnetite was observed. X-ray diffraction analysis of powdered samples detected no phyllosilicates and no crystalline clay minerals in the <1 µm size fraction. No CAI were observed in the studied thin section.

Geochemistry: Olivine (Fa0.9-34.0, N = 3), orthopyroxene (Fs2.1-2.3Wo1.4-0.8, N = 3), clinopyroxene (Fs0.9-2.7Wo41.9-40.6, N = 2). Oxygen isotopes (K. Ziegler, UNM) Analyses of six acid-washed non homogenized subsamples by laser fluorination gave, respectively δ17O -4.928, -4.401, -3.935, -2.101, -1.850, 2.263; δ18O -2.475, -1.766, -0.748, 1.112, 1.717, 6.427 ; Δ17O -3.621, -3.469, -3.540, -2.688, -2.757, -1.130 per mil.

Classification: Carbonaceous chondrite (C3, ungrouped). Oxygen isotopic compositions for this unequilibrated chondrite plot in the same sub-TFL region as for carbonaceous chondrites, but clearly not on the trends for CR, CV, CK, CO or CM chondrites.

Specimens: 20.2 g including one polished thin section at UWB; remainder with GHupe.

Data from:
  Table 0
  Line 0:
Place of purchase:Tucson
Date:P 2018 Jan
Mass (g):324.3
Shock stage:S2
Weathering grade:low
Fayalite (mol%):0.9-34.0
Ferrosilite (mol%):2.1-2.3
Wollastonite (mol%):1.4-0.8
Classifier:A. Irving, S. Kuehner, UWS; L. Garvie, ASU
Type spec mass (g):20.2
Type spec location:UWB
Main mass:GHupe
Comments:Work name GH-470; submitted by A. Irving
Plots: O isotopes:  
   and collections
ASU: Center for Meteorite Studies, Arizona State University, Tempe, Arizona 85287-1404, United States; Website (institutional address; updated 14 Jan 2012)
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
Hupe: (old address—now see GHupé or AHupé) G. and A. Hupe, 2616 Lake Youngs Court SE, Renton, WA 98058., United States (private address)
References: Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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Public domain photographs:
A. Irving   

     This is 1 of 9111 approved meteorites from (Northwest Africa) (plus 1873 unapproved names)

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