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Northwest Africa 16636
Basic information Name: Northwest Africa 16636
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 16636
Observed fall: No
Year found: 2019
Country: (Northwest Africa)
Mass:help 58.8 g
Recommended:  L6    [explanation]

This is 1 of 12995 approved meteorites (plus 11 unapproved names) classified as L6.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 30 Mar 2024
Writeup from MB 113:

Northwest Africa 16636 (NWA 16636)

(Northwest Africa)

Purchased: 2 Feb 2019

Classification: Ordinary chondrite (L6)

History: Richard (Dick) Pugh purchased a single 58.8 g whole stone from Sidi Mohamed Ismaily on February 2, 2019 at the Tucson Gem and Mineral Show in Tucson Arizona. Mr. Ismaily told Mr. Pugh that this was an unclassified northwest African Stone. Mr. Pugh donated the entire stone to Cascadia on February 7, 2019.

Physical characteristics: Physical Characteristics: The exterior of the stone is covered by a mixture of dark brown desert varnish and black patches of remnant fusion crust. The cut face is mainly light- to medium-brown-gray, grading to orange-brown near the exterior and along three cracks. Metal and sulfide grains are visible in the cut face, which is crossed by a dark gray vein complex

Petrography: (M. Hutson, V. Mugica, and A. Ruzicka, Cascadia): In thin section, most chondrules are poorly delineated in transmitted light and are well integrated with a coarse granular matrix. The thin section is cut by a vein which is substantially opaque in transmitted light, but which shows abundant visible grains of blue-green wadsleyite. BSE images show that the vein is texturally complex; one part of the vein has a sulfide-rich core surrounded on either side by a metal-sulfide-poor zone containing wadsleyite and an equant phase that is possibly majorite, and which grades into a zone filled with rounded metal-sulfide blebs near the edge of the vein. Plagioclase feldspar grains near the vein are isotropic; many grains exceed 50 μm across.

Geochemistry: Olivine and pyroxene grains are equilibrated. Olivine: Fa25.9±0.5, N=22; low-Ca pyroxene: Fs22.0±0.4Wo1.5±0.2, N=13.

Classification: Ordinary chondrite (L6) based on mineral chemistry and texture.

Specimens: Cascadia holds 50.8 g in one piece, as well as a polished thin section and material in an epoxy butt.

Data from:
  Table 0
  Line 0:
Place of purchase:Tucson, Arizona
Date:P 2 Feb 2019
Mass (g):58.8
Shock stage:S4
Weathering grade:W2
Fayalite (mol%):25.9±0.5 (N=22)
Ferrosilite (mol%):22.0±0.4 (N=13)
Wollastonite (mol%):1.5±0.2 (N=13)
Classifier:M. Hutson, V. Mugica, and A. Ruzicka, Cascadia
Type spec mass (g):50.8
Type spec location:Cascadia
Main mass:Cascadia
Comments:Lab number CML 1157; submitted by Melinda Hutson
   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)
References: Published in Meteoritical Bulletin, no. 113, in preparation (2024)
Find references in NASA ADS:
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     This is 1 of 9829 approved meteorites from (Northwest Africa) (plus 1851 unapproved names)

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