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Northwest Africa 5492
Basic information Name: Northwest Africa 5492
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 5492
Observed fall: No
Year found: 2008
Country: (Northwest Africa)
Mass:help 593 g
Meteoritical Bulletin:  MB 99  (2011)  Chondrite-ung
Recommended:  Chondrite-ung    [explanation]

This is 1 of 21 approved meteorites classified as Chondrite-ung.   [show all]
Search for other: Ungrouped chondrites
Comments: Approved 4 Jan 2011
Writeup from MB 99:

Northwest Africa 5492 (NWA 5492)

(Northwest Africa)

Purchased: 2008

Classification: Ungrouped chondrite

History: A 593 g, partially crusted stone, was purchased in Morocco by A. Aaronson in 2008 and sold to M. Farmer and J. Strope in Tucson, Arizona, in February, 2009.

Petrography: (T. Bunch and J. Wittke, NAU; M. Weisberg, KCCU): This stone is a matrix-poor mixture of (given in order of abundance) sub-mm to cm-size "barred" silicate and melt clasts (52 vol %), small Mg-rich cryptocrystalline, radial, and glassy chondrules with minor PP, barred, and POP chondrules and fragments (25 vol %) and rounded to sub-angular metal clumps (23 vol %), and grains of schreibersite, pyrrhotite, and FeS with daubreelite exsolution lamellae. In addition, another section contains a 5 mm chondrite clast with chondrules and fragments <500 μm in size and large angular clasts consisting of a fine-grained intergrowth of enstatite, metal and sulfide. Some clasts are dominated by quench-crystallized enstatite, Al-diopside, forsterite and feldspathic mesostasis together with metal enclaves. Barred clasts show shock-melted/vesiculated margins and consist of forsterite, enstatite, diopside, feldspathic glass, and metal. Metal lumps typically contain arcuate textures of tiny pyroxenes, forsterite, and FeS grains interstitial to composite metal grains. Weathering grade is W2; shock level variable, S2 to S5.

Geochemistry: Barred silicate clasts: olivine, Fa0.5; low-Ca pyroxene, Fs1.2Wo3.1 (Al2O3 = 8.4 wt. %); diopside, Fs1.4Wo47.1 (Al2O3 = 7.3 wt %). Smaller cryptocrystalline chondrules: olivine, Fa0.2 -0.7; low-Ca pyroxene, Fs0.1-0.7Wo0.5. mesostasis glass, Na2O = 2.3 - 2.83 wt % (N= 7). Metal Ni = 7.1 wt %. Oxygen isotopes: (D. Rumble, CIW) average for 4 analyses of barred silicate clasts (standard deviation): δ17O = -2.13, δ18O = 0.29 and Δ17O = -2.28 per mil. Average of 6 analyses for the smaller reduced chondrules and fragments (standard deviation): δ17O = 2.93, δ18O = 4.79, Δ17O = 0.43 per mil.

Classification: Chondrite (ungrouped), type 3. Petrologic characteristics together with the oxygen isotopic data suggest a relationship to CB chondrites for the large barred clasts, whereas the smaller reduced chondrules and fragments have oxygen isotope signatures that suggest a possible relationship to the E chondrites.

Specimens: A total of 20.7 g and one thin section are on deposit at NAU. Main mass,  MFarmer and Strope.

Data from:
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2008
Mass (g):593
Shock stage:S2-5
Weathering grade:W2
Fayalite (mol%):0.5
Ferrosilite (mol%):0.7
Wollastonite (mol%):0.4
Classifier:T. Bunch and J. Wittke, NAU; M. Weisberg, CUNY
Type spec mass (g):20.7
Type spec location:NAU
Main mass:MFarmer, J. Strope
Comments:Submitted by Bunch
Plots: O isotopes:  
   and collections
KCCU: Kingsborough College of the City University of New York, Brooklyn, NY 11235, United States (institutional address; updated 28 Dec 2011)
NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012)
Aaronson: Sahara Overland Ltd., Harhora, Temara, 12000, Morocco (private address; updated 3 Jan 2010)
CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address)
MFarmer: Michael Farmer, P.O. Box 86059, Tucson, AZ 85754-6059, United States; Website (private address)
Strope: 421 Fourth Street, Glen Dale, WV 26038, United States; Website (private address)
References: Published in Meteoritical Bulletin, No. 99, April 2012, MAPS 47, E1-E52 (2012) [published online only]
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     This is 1 of 9429 approved meteorites from (Northwest Africa) (plus 1876 unapproved names)

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