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Northwest Africa 11999
Basic information Name: Northwest Africa 11999
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11999
Observed fall: No
Year found: 2011
Country: (Northwest Africa)
Mass:help 294 g
Classification
  history:
Recommended:  Eucrite    [explanation]

This is 1 of 409 approved meteorites classified as Eucrite.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 6 Oct 2018
Writeuphelp
Writeup from MB 107:

Northwest Africa 11999 (NWA 11999)

(Northwest Africa)

Purchased: 2011 Feb

Classification: HED achondrite (Eucrite)

History: Sample purchased by D. Gregory at the Tucson Gem and Mineral show in 2011. Sample originally named "ROM 057" and is listed in ROM catalogues as LM58492.

Physical characteristics: The meteorite is a flattened fist size sample with a dark-black patchy fusion crust, weathered to expose a light orange surface. The interior of the sample is pale gray with a fine-grained matrix and small crystalline clasts visible.

Petrography: Sample bears gabbroic clasts in a fine-grained fragmented matrix. Clasts range in size from 402-5500 µm and are composed of pyroxene and plagioclase. The fragmented matrix is of the same mineralogic composition and grains range in size from microcrystalline to 200 μm. Exsolution lamellae are visible in pyroxene grains.

Geochemistry: Mineral compositions and geochemistry: There is no difference in chemistry between the clasts and matrix. Low calcium pyroxenes have a composition of Fs54.9±3.1Wo 4.8±3.9 FeO/MnO (wt%) = 29.6±0.7 (n=22). Augite has a composition of Fs24.3±1.0Wo42.8±1.3 FeO/MnO (wt%) = 29.7±1.1 (n=19). Plagioclase An91.6±0.8 (An90.3-93.7, n=39)

Classification: (V. Di Cecco, ROM) Sample is an equilibrated monomict basaltic eucrite breccia. Lamellae and compositions suggest the sample has experienced thermal equilibration. Mineral chemistry suggests the sample is a basaltic eucrite.

Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Tucson Gem and Mineral Show
Date:P 2011 Feb
Mass (g):294.42
Pieces:1
Class:Eucrite
Shock stage:low
Weathering grade:low
Classifier:V. Di Cecco, ROM
Type spec mass (g):22.11
Type spec location:ROM
Main mass:Gregory
Comments:Submitted by V. Di Cecco, ROM
Institutions
   and collections
ROM: Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada (institutional address; updated 18 Oct 2011)
Gregory: David Gregory, 230 First Avenue, Suite 108, St. Thomas, Ontario N5R 4P5, Canada (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 107, in preparation (2018)
Find references in NASA ADS:
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Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 6528 approved meteorites from (Northwest Africa) (plus 2021 unapproved names)

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