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Sayh al Uhaymir 493
Basic information Name: Sayh al Uhaymir 493
     This is an OFFICIAL meteorite name.
Abbreviation: SaU 493
Observed fall: No
Year found: 2009
Country: Oman
Mass:help 134 g
Meteoritical Bulletin:  MB 99  (2011)  Achondrite-ung
Recommended:  Achondrite-ung    [explanation]

This is 1 of 150 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 29 Dec 2010
Writeup from MB 99:

Sayh al Uhaymir 493 (SaU 493)        20°32’N, 57°18’E

Al Wusta, Oman

Found: 5 Apr 2009

Classification: Ungrouped achondrite

History: A small stone was found on desert pavement by Michael Farmer on April 5, 2009.

Physical characteristics: A fresh, partly fusion-crusted, dark stone weighing 134 g.

Petrography: (A. Irving and S. Kuehner, UWS): The overall texture is that of a medium-grained (mostly 100-400 μm), annealed igneous cumulate. The specimen is composed predominantly of exsolved pigeonitic pyroxene (with a distinctive clove brown color in transmitted light) and calcic plagioclase, with accessory ilmenite, Ti-chromite (commonly in lamellar intergrowths with ilmenite), silica polymorph, baddeleyite, iron sulfide and rare hematite. Olivine and metal are absent. Plagioclase is heterogeneously distributed in small patches, as well as occurring with pyroxene throughout the specimen. Pyroxene grains exhibit coarse, planar exsolution blades of augite within low-Ca pyroxene. Both types of pyroxene have oxide sum deficiencies and apparent cation excesses on a 6-oxygens per molecule basis, which are indicative of significant ferric iron (10% in the orthopyroxene and 14% in the clinopyroxene), as confirmed by Mössbauer spectrometry on whole sample powder (by T. Seda, WWU).

Geochemistry: Low-Ca pyroxene (Fs56.3Wo2.9, FeO/MnO = 25.5, Fe2O3 (from stoichiometry) = 3.5 wt.%), Ca-pyroxene (Fs25.3Wo42.3, FeO/MnO = 27.0, Fe2O3 (from stoichiometry) = 2.3 wt.%), plagioclase (An88.2-89.7Or0.7). Oxygen isotopes (D. Rumble, CIW): replicate analyses of acid-washed whole subsamples by laser fluorination gave, respectively: δ18O = 3.41, 3.53; δ17O = 1.54, 1.59; Δ17O = -0.255, -0.271 per mil. Bulk composition (M. Gellissen, XRF, Koln; C. Herd, ICPMS, UAb): analyses of powder prepared from interior material gave (in wt.%): SiO2 48.6, Al2O3 12.1, FeO 18.5, MgO 6.7, CaO 10.1; (in ppm) La 1.1, Ce 2.9, Nd 2.6, Sm 1.1, Yb 1.5, Lu 0.22 Ni 2.3.

Classification: Achondrite, ungrouped. The degree of weathering is very low. Although this specimen has some similarities to cumulate eucrites and its oxygen isotopic composition is within the range for eucrites, the lack of metal coupled with the presence of significant ferric iron in the constituent minerals make it distinctive and unique.

Specimens: A total of 20.1 g of type material and two polished thin sections are on deposit at UWS. The main mass is held by MFarmer.

Data from:
  Table 0
  Line 0:
State/Prov/County:Al Wusta
Date:5 Apr 2009
Mass (g):134
Shock stage:low
Weathering grade:very low
Ferrosilite (mol%):56.3; 25.3
Wollastonite (mol%):2.9; 42.3
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):20.1
Type spec location:UWS
Main mass:MFarmer
Comments:Submitted by A. Irving
Plots: O isotopes:  
   and collections
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
UAb: 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB, T6G 2E3, Canada, Canada; Website (institutional address; updated 17 Oct 2011)
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)
Koln: Universität zu Köln, Institut für Mineralogie und Geochemie, Zülpicher Straße 49 b, 50674 Köln, Germany (institutional address; updated 7 Nov 2015)
WWU: Western Washington University, Bellingham, WA, United States (institutional address; updated 29 Dec 2010)
References: Published in Meteoritical Bulletin, No. 99, April 2012, MAPS 47, E1-E52 (2012) [published online only]
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     Recommended::   (20° 32'N, 57° 18'E)

     This is 1 of 1753 approved meteorites from Al Wusta, Oman (plus 81 unapproved names)
     This is 1 of 3998 approved meteorites from Oman (plus 441 unapproved names)
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