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Northwest Africa 4590
Basic information Name: Northwest Africa 4590
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 4590
Observed fall: No
Year found: 2006
Country: Algeria
Mass:help 213 g
Meteoritical Bulletin:  MB 92  (2007)  Angrite
Recommended:  Angrite    [explanation]

This is 1 of 51 approved meteorites classified as Angrite.   [show all]
Search for other: Achondrites, Angrites
Comments: Approved 24 Jul 2007
Writeup from MB 92:

Northwest Africa 4590                    30°19.025'N, 4°56.573'W


Find: June 2006

Achondrite (angrite)

History: Scattered fragments from a small stone which appears to have shattered upon landing recently were recovered from an area of ~40 m2 in the Morocco-Algeria border zone, 21 km SSW of Tamassint oasis and 18 km S of Agoult, Morocco. G. Hupé purchased all the recovered material in June 2006 in Tagounite, Morocco. He then traveled to Tamassint and was shown the location by the original find and measured GPS coordinates.

Physical characteristics: Fragments totaling 212.8 g of a very friable specimen composed of coarse yellow-green, black and white grains; very fresh with preserved shiny, black fusion crust on some pieces, and minor pale orange terrestrial weathering coatings on some broken surfaces.

Petrography: (A. Irving and S. Kuehner, UWS) Coarse grained (mostly 0.6-1.6 mm, but some olivine grains up to 12 mm) with a cumulate texture and composed of clinopyroxene (33 vol%, with rare pigeonite exsolution lamellae), pure anorthite (28 vol%), olivine (14 vol%, with prominent subparallel exsolution lamellae (10-50 microns wide) of kirschsteinite), kirschsteinite (5 vol%, with thin exsolution lamellae of olivine), ulvöspinel (18 vol%), and accessory glass, troilite, merrillite, Ca-silicophosphate and kamacite (making up the remaining 5 vol%). Some anorthite occurs as subhedral grains partially enclosed within large ulvöspinel grains, but most occurs as intercumulus aggregates. Clinopyroxene is strongly zoned with paler colored, corroded cores surrounded by darker purple-brown mantles and distinct rims. Thin (5-50 µm wide) discontinuous, curvilinear zones of glass are present on some grain boundaries (notably those between anorthite and ulvöspinel, but also around and cutting across troilite grains), and are associated with secondary clinopyroxene, kirschsteinite, olivine, anorthite and troilite grains; these films of glass+daughter minerals truncate kirschteinite exsolution lamellae in adjacent olivine. This angrite is unlike other known specimens, having neither a fine-grained quench or ophitic/intesertal basaltic texture nor a coarse metamorphic texture.

Mineral compositions and geochemistry: Clinopyroxene (Fs20.8-33.3Wo53-54.9; FeO/MnO = 85-278), olivine host (Fa72.6-74.7Ln3.5-3.6; FeO/MnO = 70-87), kirschsteinite lamellae (Fa44.7-45.4Ln46-47.2; FeO/MnO = 73-82), kirschsteinite host (Fa46.6-47.5Ln43.6-45.5; FeO/MnO = 63-68), olivine lamellae (Fa75-76.7Ln2.7-2.8; FeO/MnO = 71-74). Oxygen Isotopes: (D. Rumble, CIW) Analyses of two aliquots of acid-washed mineral fragments by laser fluorination gave, δ18O = 3.845, 3.881; δ17O = 1.927, 1.967; Δ17O = 0.0956, 0.0745 (all ‰).

Classification: Achondrite (angrite).

Specimens: A total of 20.01 g of sample, two polished thin sections and two polished mounts are on deposit at UWS, and 4 g at PSF. GHupé holds the main mass.

Writeup from MB 99:

Correction: The oxygen isotope composition listed for NWA 4590 was incorrect in Meteoritical Bulletin 92.  The correct value is: 17O = -0.0956, -0.0745 ‰.

Data from:
  Table 2
  Line 112:
Place of purchase:Tagounite, Morocco
Mass (g):212.8
Type spec mass (g):20.01
Plots: O isotopes:  
   and collections
PSF: Planetary Studies Foundation,10 Winterwood Lane, Unit B, Galena, Illinois 61036-9283, United States; Website (institutional address; updated 1 Dec 2011)
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address)
GHupé: Gregory M. Hupé, 9003 Placid Lakes Blvd., Lake Placid, FL 33852, United States; Website (private address)
References: Published in Meteoritical Bulletin, no. 92, MAPS 42, 1647-1694 (2007)
Published in Meteoritical Bulletin, No. 99, April 2012, MAPS 47, E1-E52 (2012) [published online only]
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     Recommended::   (30° 19' 1"N, 4° 56' 34"W)

     This is 1 of 35 approved meteorites from Bechar, Algeria (plus 1 unapproved name)
     This is 1 of 1356 approved meteorites from Algeria (plus 30 unapproved names) (plus 4 impact craters)
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