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Northwest Africa 12817
Basic information Name: Northwest Africa 12817
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12817
Observed fall: No
Year found: 2018
Country: (Northwest Africa)
Mass:help 127 g
Classification
  history:
Recommended:  Eucrite-unbr    [explanation]

This is 1 of 92 approved meteorites classified as Eucrite-unbr.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 18 Aug 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12817 (NWA 12817)

(Northwest Africa)

Purchased: 2018

Classification: HED achondrite (Eucrite, unbrecciated)

History: Marc Jost acquired the 12 7g sample from Giorgio Tomelleri at the St Marie aux Mines show in 2018.

Physical characteristics: The exterior is covered by a ~1mm thick, dark brown, bumpy fusion crust. Pyroxenes protrude through the surface of the crust as blocky, brown crystals. The cut face shows the interior is composed of light orange and white interlocking crystals with an igneous texture.

Petrography: Description and classification (A. Love, App): Sample is a coarse-grained, unbrecciated, ophitic-textured basalt with 990 μm euhedral to subhedral plagioclase laths enclosed by 4 mm exsolved pigeonites. Some margins of pyroxenes show they have been recrystallized into smaller sub grains with 120º grain boundaries. Additional minerals are: ilmenite, chromite, zircon, phosphate and a silica polymorph.

Geochemistry: (A. Love, App) Low Ca pyroxene Fs61.9±0.9Wo5.3±1.0 (Fs60.2-63.1Wo4.1-7.2), Fe/Mn=30.4±0.4, Mg#=34.8, N=22; high Ca pyroxene Fs32.7±0.5 Wo39.9±0.6 (Fs31.7-33.7Wo38.9-41.2), Fe/Mn=32.3±0.9, N=15; plagioclase An89.1±2.1Or0.4±0.1 (An86.3-91.4Or0.2-0.7), N=8.

Classification: Achondrite (gabbroic eucrite, unbrecciated). Based on ophitic texture, equilibrated compositions, Fe/Mn and Mg# of pigeonites, this sample is a coarse-grained, unbrecciated, equilibrated gabbroic eucrite. This sample corresponds to a type 6 eucrite of Takeda and Graham (1991) based upon inversion of original pigeonite and equilibrated compositions of pyroxenes.

Specimens: Marc Jost (SJS) holds the main mass. 2 slices weighing 20.5 g, a mount and polished thin section are on deposit at App.

Bibliography:
  • H. Takeda and A.L. Graham (1991) Degree of equilibration of eucritic pyroxenes and thermal metamorphism of the earliest planetary crust. Meteoritics 26 129-134. (link)
Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:St Marie aux Mines, France
Date:P 2018
Mass (g):127
Pieces:1
Class:Eucrite-unbr
Shock stage:M-S2
Weathering grade:low
Ferrosilite (mol%):61.9±0.9; 32.7±0.5
Wollastonite (mol%):5.3±1.0; 39.9±0.6
Magnetic suscept.:2.84
Classifier:A. Love, App
Type spec mass (g):20.5
Type spec location:App
Main mass:Marc Jost (SJS)
Finder:Unknown
Comments:Submitted by Anthony Love
Institutions
   and collections
App: Department of Geology, 572 Rivers St., Appalachian State University, Boone, NC 28608, United States (institutional address; updated 7 Mar 2013)
SJS: Space Jewels Switzerland, 2555 Brügg, Switzerland (private address; updated 3 Jan 2010)
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 6900 approved meteorites from (Northwest Africa) (plus 2035 unapproved names)

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