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Ramlat as Sahmah 309
Basic information Name: Ramlat as Sahmah 309
     This is an OFFICIAL meteorite name.
Abbreviation: RaS 309
Observed fall: No
Year found: 2009
Country: Oman
Mass:help 1435 g
Meteoritical Bulletin:  MB 101  (2012)  Brachinite
Recommended:  Brachinite    [explanation]

This is 1 of 58 approved meteorites classified as Brachinite.   [show all]
Search for other: Brachinites, Primitive achondrites
Comments: Approved 21 Sep 2012
Writeup from MB 101:

Ramlat as Sahmah 309 (RaS 309)        20°45.948’N, 55°26.152’E

Al Wusta, Oman

Found: 17 Feb 2009

Classification: Primitive achondrite (Brachinite)

History: Three stones (1218.4, 181.9, 28.1 g) were found during a search for meteorites by U. Eggenberger, E. Gnos, E. Janots and F. Zurfluh. An additional stone of 7.054 g was found nearby on 11 January 2010 by U. Eggenberger, E. Gnos, N. Greber and F. Zurfluh.

Physical characteristics: The four stones have a combined mass of 1435.43 g. All stones are wind-ablated and show no fusion crust. The largest stone (16 × 7 × 4 cm) of dominantly brown color has one particularly flat surface (10 × 6 cm) showing an enrichment of green Ca-rich pyroxenes. Additional similar layers are present parallel to the exposed one in the interior of the stone, as seen on the side of the stone and in X-ray tomographic sections.

Petrography: (B. Hofmann, NMBE, F. Zurfluh, E. Gnos, MHNGE): The rock shows an equigranular texture (mean grain size approx. 0.5 mm) and consists of ~94 vol% olivine, 4 vol% Ca-rich pyroxene (Fs9.1Wo47.4) and 1 vol% of chromite. Accessory phases are Ca-poor pyroxene, metal, troilite (both occurring as grains a few mm in size in silicates) and graphite (occurring as inclusions in olivine and chromite). The rock is weakly shocked (S2). Strong weathering, metal is replaced by hydroxides where not completely enclosed in silicates.

Geochemistry: Olivine composition Fa33.1, pyroxene composition Fs9.1Wo47.4, accessory metal has 30-55 wt% Ni A bulk analysis showed Fe/Mn (wt%) = 74.3, Ni = 510 ppm. Oxygen isotopes (I.A. Franchi and R.C. Greenwood, OU): Analyses of a bulk sample (Fe-hydroxides removed with ethanolamine thioglycollate) yielded δ17O = 2.09, δ18O = 4.37, and Δ17O = -0.19 per mil (mean of two replicates).

Classification: Based on texture, mineralogy and oxygen isotopic composition this is a brachinite.

Specimens: All at NMBE.

Data from:
  Table 0
  Line 0:
State/Prov/County:Al Wusta
Origin or pseudonym:desert plain
Date:17 Feb 2009
Mass (g):1435.43
Fayalite (mol%):33.1
Ferrosilite (mol%):9.1
Wollastonite (mol%):7.4
Classifier:F. Zurfluh IFGBE, B. Hofmann NMBE, E. Gnos MHNGE
Type spec mass (g):1428.4
Type spec location:NMBE
Main mass:NMBE
Finder:U. Eggenberger, E. Gnos, E. Janots, F. Zurfluh
Comments:Submitted by B.A. 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)
References: Published in Meteoritical Bulletin, no. 101, MAPS 50, 1661, September 2015
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     Recommended::   (20° 45' 57"N, 55° 26' 9"E)

     This is 1 of 1759 approved meteorites from Al Wusta, Oman (plus 75 unapproved names)
     This is 1 of 4006 approved meteorites from Oman (plus 436 unapproved names)
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