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Northwest Africa 11040
Basic information Name: Northwest Africa 11040
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11040
Observed fall: No
Year found: 2016
Country: (Northwest Africa)
Mass:help 13 g
Meteoritical Bulletin:  MB 106  (2018)  Eucrite-unbr
Recommended:  Eucrite-unbr    [explanation]

This is 1 of 122 approved meteorites classified as Eucrite-unbr.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 13 Jan 2017
Writeup from MB 106:

Northwest Africa 11040 (NWA 11040)

(Northwest Africa)

Purchased: 2016

Classification: HED achondrite (Eucrite, unbrecciated)

History: A complete stone was purchased from Sean Tutorow’s eBay operation by Jason Utas

Physical characteristics: One rough-surfaced, fusion crusted individual stone.

Petrography: The texture is subophitic and unbrecciated. The mineralogy is typical eucritic (pyroxene and plagioclase with minor ilmenite, silica, Cr-spinel, troilite and trace olivine), except for an unusually high proportion of pure-Fe metal, originally roughly 0.6 vol%, although roughly 1/3 of that original metal has been replaced by Fe-oxides. Plagioclase is up to 4.8 mm in length (4.8 × 0.2 mm). Metal occurs dominantly as blocky grains, typically 0.1-0.2 mm across. Manifestations of thermal annealing, such as exsolution lamellae in pyroxene, are nearly undetectable, and about 30 vol% of the rock is mesostasis, so fine-grained as to appear opaque in transmitted light. The shock class is intermediate based on undulose extinction and planar fractures in pyroxene.

Geochemistry: Pyroxenes are compositionally diverse and complex. For the most part, major-element compositions show a pattern typical of low-thermal-metamorphism eucrites (cf. Pasamonte), fanning out from a tight cluster at Fs29Wo5 (cores of larger grains) in the general direction of Fs45Wo30 (rims and fine-grained areas). However, in a few locales, pyroxene in fine-scale intergrowth with silica (pyroxene widths typically 1-3 microns) consists of a remarkably low-Ca variety, Fs49-51Wo1.0-1.5, along with a far lesser proportion of high-Ca composition (near Fs39Wo44). Also, curvy veinlike patches of oddly low-Ca composition (notably bright in backscattered electron images) are sprinkled within the cores of large pyroxenes. The average measured pyroxene composition (n=258) is Fs37Wo16 with FeO/MnO = 29±1.5. Plagioclase (n=23) is An79-91, average An84.6±3.4, excluding one anomalous analysis, An98. Olivine (n=5) is Fa69-71. Spinel (9 analyses of a single 0.6-mm grain) has Cr/(Al+Cr) ranging from 0.59-0.76. The Fe-metal has undetectable Ni (less than 0.1 wt%) and 0.15-0.23 wt% Co. INAA bulk-rock results include Na = 4.1 mg/g, Sc = 28 μg/g, Cr = 1.9 mg/g, Fe = 138 mg/g, Sm = 3.2 μg/g.

Classification: The meteorite is an unbrecciated eucrite.

Data from:
  Table 0
  Line 0:
Place of purchase:eBay
Date:P 2016
Mass (g):13
Weathering grade:moderate
Ferrosilite (mol%):17-54
Classifier:P. Warren, UCLA
Type spec mass (g):2.98
Type spec location:UCLA
Main mass:Jason Utas
Comments:Submitted by Paul Warren
   and collections
UCLA: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, United States (institutional address; updated 17 Oct 2011)
References: Published in Gattacceca J., Bouvier A., Grossman J., Metzler K., and Uehara M. (2019) Meteoritical Bulletin, no. 106. Meteorit. Planet. Sci. 54 in press.
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     This is 1 of 8674 approved meteorites from (Northwest Africa) (plus 1882 unapproved names)

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