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Northwest Africa 8671
Basic information Name: Northwest Africa 8671
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8671
Observed fall: No
Year found: 2014
Country: (Northwest Africa)
Mass:help 164.2 g
Classification
  history:
Recommended:  Eucrite-an    [explanation]

This is 1 of 8 approved meteorites classified as Eucrite-an.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 19 Jan 2018
Revised 8 Jun 2018: Reclassified
Writeuphelp
Writeup from MB 107:

Northwest Africa 8671 (NWA 8671)

(Northwest Africa)

Purchased: 2014 May

Classification: HED achondrite (Eucrite)

History: Purchased in Morocco by Ali and Mohammed Hmani in May 2014 and said to have been found near Foum El Hisn, Morocco.

Physical characteristics: Single stone (164.2 g) lacking fusion crust. The fresh interior is relatively coarse grained and composed of subequal amounts of dark gray pyroxene and beige plagioclase.

Petrography: (A. Irving and S. Kuehner, UWS) This is a very unusual specimen consisting of dispersed, angular domains of coarse, polygranular, birefringent, calcic plagioclase separated by regions of recystallized clinopyroxene. The plagioclase domains have irregular geometric shapes with re-entrant angles, and exhibit marginal reaction zones against clinopyroxene composed of ferropigeonite plus fayalitic olivine. The main regions of clinopyroxene contain numerous irregularly distributed, small patches with two distinctly different compositions: one low in Ca and the other higher in Ca. No high-Ca augite was found. Accessory minerals are silica polymorph, Al-bearing chromite and troilite.

Geochemistry: Low-Ca pyroxene (Fs47.9-49.1Wo5.5-4.4, FeO/MnO = 28-29, N = 3), pigeonite (Fs36.3-34.7Wo10.8-7.6, FeO/MnO = 26-28, N = 3), ferropigeonite rims (Fs52.5-55.5Wo21.6-16.5, FeO/MnO = 30, N = 2), fayalite (Fa82.2-82.9, FeO/MnO = 39), plagioclase (An91.4-93.0Or0.1, N = 2). Oxygen isotopes (K. Ziegler, UNM): acid-washed subsamples analyzed by laser fluorination gave δ17O = 1.736, 1.642, 1.694; δ18O = 3.847, 3.688, 3.776; Δ17O = -0.295, -0.305, -0.300 per mil

Classification: Eucrite (unbrecciated, partially melted). The overall texture and reaction zones on plagioclase aggregates are unique among eucrites, and indicate that this specimen underwent a partial melting event subsequent to its igneous crystallization.

Specimens: 20.1 g including one polished thin section at UWB. The remainder is held by Hmani Inc.


Writeup from MB 107:

Reclassification of Northwest Africa 8671 (NWA 8671)

(Northwest Africa)

Find: 2014

Classification: Eucrite (anomalous). The disequilibrium textures in this specimen are unique among eucrites and the absence of high Ca augite is very unusual. Furthermore, the oxygen isotope composition plots to more negative Δ17O values than for all other analyzed eucrites.

Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2014 May
Mass (g):164.2
Pieces:1
Class:Eucrite
Shock stage:high
Weathering grade:low
Ferrosilite (mol%):47.9-49.1; 36.3-34.7
Wollastonite (mol%):5.5-4.4; 10.8-7.6
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):20.1
Type spec location:UWB
Main mass:Hmani Inc.
Comments:OT15; submitted by A. Irving
Plots: O isotopes:  
Institutions
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
Hmani: A. Hmani Moroccan Imports, 13 rue Jules Hardouin Mansart, 92600 Asnières, France (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 107, in preparation (2018)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 6423 approved meteorites from (Northwest Africa) (plus 2023 unapproved names)

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