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Northwest Africa 16662
Basic information Name: Northwest Africa 16662
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 16662
Observed fall: No
Year found: 2021
Country: (Northwest Africa)
Mass:help 325 g
Classification
  history:
Recommended:  L3    [explanation]

This is 1 of 859 approved meteorites (plus 2 unapproved names) classified as L3.   [show all]
Search for other: L chondrites, L chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
Comments: Approved 11 Apr 2024
Writeuphelp
Writeup from MB 113:

Northwest Africa 16662 (NWA 16662)

(Northwest Africa)

Purchased: Jun 2021

Classification: Ordinary chondrite (L3)

History: Mr. Jasper Spencer purchased fourteen pieces (325 g) of weathered stones containing well defined chondrules from a Mauritanian dealer in June 2021 via Facebook Messenger. The single largest stone is 71 g. Mr. Jasper sent pieces from five stones (totaling 50 g) to Cascadia for classification.

Physical characteristics: All of the pieces received by Cascadia have cut faces, with exteriors covered by a weathered veneer; none had remnant fusion crust. Both cut faces and the exterior are medium-to-dark brown in color. Distinct chondrules are visible on all surfaces.

Petrography: (M. Hutson, A. Ruzicka, Cascadia): The thin section shows crisply defined chondrules set in an opaque matrix. BSE images show chondrules containing normally-zoned olivine grains and low-Ca pyroxene grains with crystallite-filled glassy mesostases, surrounded by a fine-grained clastic matrix; most grains in the groundmass are ~10 µm across, with patches of very fine grains (~ 1 µm across). Approximately 85-90% of the metal and troilite in the section has been replaced by terrestrial weathering products. Altogether, approximately 5% of the area of the thin section appears to be composed of terrestrial iron hydroxides, metal, and sulfide grains.

Geochemistry: Olivine: Fa21.6±9.8, N=88; low-Ca pyroxene: Fs:13.6±10.3Wo1.6±1.4, N=21.

Classification: Ordinary chondrite (L3). The mineral chemistry is consistent with either an L3 or an LL3 chondrite. Estimated metal + sulfide + weathering product is more consistent with L-chondrite. Magnetic susceptibility and electrical conductivity were measured twice on two different stones using the "Meteorite meter" described in Uehara and Gattacceca (2023). log χ (× 10-9 m3/kg) = 4.45±0.17 and the C-index=2.2±0.08 (N=4); these values are consistent with a heavily weathered L-chondrite, but not a heavily weathered LL-chondrite.

Specimens: Cascadia holds 47 g in four pieces, as well as a polished thin section and material in an epoxy butt; Mr. Jasper Spencer holds the main mass.


Bibliography:
  • Uehara M. and Gattacceca J. (2023) The “Meteorite meter”: A handheld instrument for the combined measurement of magnetic susceptibility and electrical conductivity, with application to meteorite identification and classification. Meteoritics & Planetary Science 58, 1629–1641. (link)
Data from:
  MB113
  Table 0
  Line 0:
Place of purchase:FB Messenger
Date:P Jun 2021
Mass (g):325
Pieces:14
Class:L3
Shock stage:S3
Weathering grade:W3
Fayalite (mol%):21.6±9.8 (N=88)
Ferrosilite (mol%):13.6±10.3 (N=21)
Wollastonite (mol%):1.6±1.4 (N=21)
Magnetic suscept.:4.45±0.17 (N=4)
Classifier:M. Hutson, V. Mugica, and A. Ruzicka, Cascadia
Type spec mass (g):50
Type spec location:Cascadia
Main mass:Mr. Jasper Spencer
Comments:Lab number CML 1443; submitted by Melinda Hutson
Institutions
   and collections
Cascadia: Cascadia Meteorite Laboratory, Portland State University, Department of Geology, Room 17 Cramer Hall, 1721 SW Broadway, Portland, OR 97201, United States; Website (institutional address; updated 28 Oct 2011)
Catalogs:
References: Published in Meteoritical Bulletin, no. 113, in preparation (2024)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 9829 approved meteorites from (Northwest Africa) (plus 1851 unapproved names)

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