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Northwest Africa 12777
Basic information Name: Northwest Africa 12777
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12777
Observed fall: No
Year found: 2015
Country: (Northwest Africa)
Mass:help 89.3 g
Classification
  history:
Recommended:  Eucrite    [explanation]

This is 1 of 441 approved meteorites (plus 1 unapproved name) classified as Eucrite.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 11 Oct 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12777 (NWA 12777)

(Northwest Africa)

Purchased: 2015

Classification: HED achondrite (Eucrite)

History: Catalogued at the ROM as sample LM57448.

Physical characteristics: Visible fusion crust showing minimal weathering. Interior of the sample shows a pale orange color possibly due to caliche formation. Different clasts visible inside the sample.

Petrography: Polymict eucrite breccia containing several clasts, all of which have Opx, Cpx and plagioclase. Matrix is comprised of phenocrysts of pyroxene and plagioclase laths surrounded by fine-graind material of the same composition. Clasts can be described as 1) a very fine grained clast of disequilibrated texture, containing Plag, Opx and Cpx; 2) a lighter clast containing larger plagioclase and pyroxene grains, showing annealed or thermally-metamorphosed texture; 3) several basaltic clasts with needle-shaped plagioclase laths. Whole rock shows severe brecciation and crushing, some clast show more thermal and shock deformation.

Geochemistry: Mineral composition and geochemistry: Plagioclase An92.4±3.8 (n=10). Low-Ca pyroxene composition: Fs23.3±9.3Wo4.3±1.2 and Mg# 39.0-70.8 (n=19); High-Ca pyroxene composition: Fs24.9±11.9Wo24.1±17.7, Mg# 38.5-70.2 (n=9)

Classification: (A. Cernok, ROM) Texture and compositions suggest the sample is a polymict eucrite breccia. Lack of clear Opx-dominated clasts excludes the possibility of this meteorite being a howardite.

Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:Tucson Gem and Mineral Show
Date:P 2015
Mass (g):89.27
Pieces:2
Class:Eucrite
Shock stage:low
Weathering grade:low
Ferrosilite (mol%):23.3±9.3, 24.9±11.9
Wollastonite (mol%):4.3±1.2, 24.1±17.7
Classifier:A. Cernok, ROM
Type spec mass (g):17.9
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. 108, in preparation (2019)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 6968 approved meteorites from (Northwest Africa) (plus 2012 unapproved names)

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