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Northwest Africa 8739
Basic information Name: Northwest Africa 8739
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8739
Observed fall: No
Year found: 2013
Country: (Northwest Africa)
Mass:help 126.2 g
Classification
  history:
Meteoritical Bulletin:  MB 104  (2015)  Eucrite-pmict
Recommended:  Eucrite-pmict    [explanation]

This is 1 of 339 approved meteorites classified as Eucrite-pmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 16 Feb 2015
Writeuphelp
Writeup from MB 104:

Northwest Africa 8739 (NWA 8739)

(Northwest Africa)

Purchased: 2013

Classification: HED achondrite (Eucrite, polymict)

History: Purchased by Blaine Reed from Eegooblago Meteorites at the Denver Gem and Mineral Show 2013.

Physical characteristics: Single stone, smooth brown weathered exterior. A saw cut reveals a breccia with scattered clasts up to ~1 cm set a in fine-grained, gray, groundmass.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows ~55% pyroxene and ~40% plagioclase. Accessory silica, troilite, chromite, ilmenite, and Fe-metal. Several different microtextures are present; there are numerous fragmental pyroxene and plagioclase grains up to ~300 μm, clasts with quench mesostasis and skeletal pyroxenes, clasts with acicular plagioclase or pyroxene intergrowths. Most pyroxenes show strong igneous zoning with En-rich cores and Fs/Wo-rich rims, however there is also a minor population of pyroxenes that appear to be more equilibrated with fine exsolution lamellae.

Geochemistry: (C. Agee and N. Muttik, UNM) EMPA. Pyroxene Fs45.6±10.9Wo10.1±3.0, Fe/Mn=31±2, n=25; plagioclase Or0.6±0.4Ab10.3±3.6An 89.1±4.0, n=4. Oxygen isotopes (K. Ziegler, UNM): acid-washed material analyzed in 2 replicates by laser fluorination gave, respectively δ18O=3.420, 2.990; δ17O=1.508, 1.312; Δ17O= -0.298, -0.267 (all per mil).

Classification: Achondrite (polymicy eucrite) Unequilibrated basalt with a range of pyroxene compositions consistent with Type-2 eucrites (Takeda and Graham, 1991); a polymict breccia similar in texture and composition to Pasamonte.

Specimens: 20.0 g including a probe mount on deposit at UNM, Reed holds the main mass.

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:
  MB104
  Table 0
  Line 0:
Place of purchase:Denver
Date:P 2013
Mass (g):126.2
Pieces:1
Class:Eucrite-pmict
Shock stage:high
Weathering grade:moderate
Ferrosilite (mol%):45.6±10.9
Wollastonite (mol%):10.1±3.0
Classifier:C. Agee, UNM
Type spec mass (g):20
Type spec location:UNM
Main mass:Blaine Reed
Comments:Field name BR-89; submitted by C. Agee
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)
Reed: Blaine Reed, P.O. Box 1141, Delta, CO 81416, United States; Website (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 104, MAPS 52, 2284, Octover 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12930/full
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 6877 approved meteorites from (Northwest Africa) (plus 2037 unapproved names)

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