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Northwest Africa 12912
Basic information Name: Northwest Africa 12912
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12912
Observed fall: No
Year found: 2016
Country: (Northwest Africa)
Mass:help 30.9 g
Meteoritical Bulletin:  MB 108  (2020)  LL3
Recommended:  LL3    [explanation]

This is 1 of 496 approved meteorites classified as LL3.   [show all]
Search for other: LL chondrites, LL chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
Comments: Approved 21 Nov 2019
Writeup from MB 108:

Northwest Africa 12912 (NWA 12912)

(Northwest Africa)

Purchased: 12 Dec 2016

Classification: Ordinary chondrite (LL3)

History: BBaecker purchased an NWA meteorite on Ebay on December 12, 2016, and donated seven pieces to Cascadia on February 4, 2017.

Physical characteristics: Cascadia received seven small pieces that are medium- to dark-brown with patches of tan caliche on surfaces.

Petrography: (M. Hutson, A. Ruzicka, R. Kostynick, Cascadia): Distinct chondrules set in an opaque background are visible in thin section. Metal and sulfide have been replaced by iron hydroxides, and plucked, leaving holes in the poorly-polished thin section. No shock veins were visible using the optical microscope. Strong zoning of silicates is evident in BSE images. Chondrules are partly surrounded by a melt matrix. Small (?50 μm across) chromite-plagioclase patches are visible, mainly inside larger pyroxene grains. Chondrules average apparent diameter 0.89 mm (N=18).

Geochemistry: Mineral compositions and geochemistry: Olivine and pyroxene grains are highly unequilibrated: Fa28.6±8.1, N=32; Fs13.5±9.5Wo1.7±1.6, N=17.

Classification: Ordinary chondrite (LL3) based on olivine fayalite content and average chondrule diameter.

Specimens: Cascadia holds 6.6 g in eight pieces, in addition to a polished thin section and a mounted butt. The main mass is held by BBaecker: Bastien Baecker, Huntsville, AL

Data from:
  Table 0
  Line 0:
Place of purchase:Ebay
Date:P 12 Dec 2016
Mass (g):30.9
Shock stage:S5
Weathering grade:W4
Fayalite (mol%):28.6±8.1 (N=32)
Ferrosilite (mol%):13.5±9.5 (N=17)
Wollastonite (mol%):1.7±1.6 (N=17)
Classifier:M. Hutson and R. Kostynick, Cascadia
Type spec mass (g):6.6
Type spec location:Cascadia
Main mass:BBaecker
Comments:Lab number CML 0939; 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. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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     This is 1 of 9806 approved meteorites from (Northwest Africa) (plus 1855 unapproved names)

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