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Umm as Samim 024
Basic information Name: Umm as Samim 024
     This is an OFFICIAL meteorite name.
Abbreviation: UaS 024
Observed fall: No
Year found: 2010
Country: Oman
Mass:help 407 g
Meteoritical Bulletin:  MB 101  (2012)  Eucrite-cm
Recommended:  Eucrite-cm    [explanation]

This is 1 of 54 approved meteorites classified as Eucrite-cm.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 11 Jul 2012
Writeup from MB 101:

Umm as Samim 024 (UaS 024)        21°7.582’N, 55°31.567’E

Al Wusta, Oman

Found: 2010 Jan 8

Classification: HED achondrite (Eucrite, cumulate)

History: A single, fully crusted stone of 406.81 g was found during a search for meteorites by on a deflated plane between a dune gap.

Physical characteristics: The black fusion crust has a dark, slightly greenish appearance and shows some polygonal shrinkage cracks, small regmalypts and has some small vesicles. The shape of the meteorite and the appearance of the fusion crust features indicate this is an oriented meteorite. Cut surfaces are greenish white.

Petrography: (B. Hofmann, NMBE; F. Zurfluh, N. Greber, Bern; E. Gnos, MHNGE): The rock shows a brecciated texture with clasts ranging <1mm to 1 cm, consisting of granular cpx, plag and tridymite, and a microcrystalline matrix. The mineralogy is dominanted by large (200 μm), mostly idiomorphic and twinned Ca-poor pyroxene crystals with Ca-poor lamellae (4 mm), which also have sub-μm lamellae. The second most abundant phase is plagioclase, followed by tridymite (as determined by EDS and Raman spectroscopy), chromite and ilmenite. Accessory phases are small grains of iron metal and troilite. The sample is weakly shocked; some of the pyroxenes have planar fractures. Weathering is low, some iron grains are altered to iron hydroxides, resulting in minor local rusty staining.

Geochemistry: Orthopyroxene Fs62.5Wo5.5 (range Fs60.1-63.1Wo5-6.2), Fe/Mn=32.4; n=23; Ca-rich pyroxene (exolved augite) Fs32.2Wo41.5 (range Fs26.6-33.5Wo40.3-42.4) Fe/Mn=35.5 (28.2-39.4), n=11; Feldspar (ternary) An86.3Or0.6 (range An85.4-87.5Or0.4-0.7), ilmenite mg#=3.1, n=11. Bulk analysis by XRF showed CaO = 10.0 wt%, TiO2 = 0.66 wt%, Fe/Mn (wt) = 36. Oxygen isotopes (I. A. Franchi and R. C. Greenwood, OU): Analyses of a bulk sample yielded δ17O = 1.72±0.06‰, δ18O = 3.86±0.13‰, and Δ17O = -0.243 ± 0.004‰ (mean of two replicates).

Classification: Based on texture, mineralogy and oxygen isotopic composition this is a monomict cumulate eucrite.

Specimens: All at NMBE.

Data from:
  Table 0
  Line 0:
State/Prov/County:Al Wusta
Origin or pseudonym:desert plain
Date:2010 Jan 8
Mass (g):406.8
Ferrosilite (mol%):62.5
Wollastonite (mol%):5.5
Classifier:F. Zurfluh, Bern; B. Hofmann, NMBE; and E. Gnos, MHNGE
Type spec mass (g):406.8
Type spec location:NMBE
Main mass:NMBE
Finder:U. Eggenberger, E. Gnos, N. Greber, F. Zurfluh
Comments:Submitted by Beda Hofmann
Plots: O isotopes:  
   and collections
NMBE: Natural History Museum Bern Bernastrasse 15 CH-3005 Bern Switzerland, Switzerland; Website (institutional address; updated 2 Mar 2012)
OU: Planetary and Space Sciences Department of Physical Sciences The Open University Walton Hall Milton Keynes MK7 6AA United Kingdom, United Kingdom (institutional address; updated 8 Dec 2011)
MHNGE: Muséum d’histoire naturelle, Route de Malagnou 1, CH-1211 Genève 6 , Switzerland (institutional address; updated 27 Oct 2011)
Bern: University of Bern, University of Bern, Hochschulstrasse 4, CH-3012 Bern, Switzerland (institutional address)
References: Published in Meteoritical Bulletin, no. 101, MAPS 50, 1661, September 2015
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     Recommended::   (21° 7' 35"N, 55° 31' 34"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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