Dhofar 378


                    THE METEORITICAL BULLETIN
                 Announcement 86-1, April 5, 2002
               Sara Russell, Editor (sara.russell@nhm.ac.uk)
          Jutta Zipfel, Assoc. Ed. for Saharan Meteorites 
                  (zipfel@mpch-mainz.mpg.de)
    Jeffrey N. Grossman, Assoc. Ed. for Web (jgrossman@usgs.gov)
                 Monica M. Grady, Co-Editor 

Dhofar 378               1809.5' N, 5406.8' E
  Oman
  Found 2000 June 17
  Martian meteorite (basaltic shergottite)
A single stone of 15 g, covered with fresh black fusion crust, was 
recovered by an anonymous finder within the province of other Dhofar  
meteorites. Classification and description: (Y. Ikeda and M. Kimura, 
Dept. of Materials and Biological Sciences Ibaraki; H. Takeda,  
Chiba): It has a doleritic or microgabbroic texture, and the grain 
sizes of the main minerals (pyroxenes and plagioclase glass) are  
about 1 mm across. It consists mainly of ferroan pyroxenes (augite 
and pigeonite), and plagioclase glass with quenched plagioclase 
rims.  Minor minerals are hedenbergite, pyroxferroite, fayalite, 
silica, Ti-rich magnetite, ilmenite, sulfide, phosphate, and 
rhyolitic glass.  The Fe/(Mg+Fe) ratios of pyroxenes (augite and 
pigeonite) range from 0.40 to more than 0.90, those of hedenbergite 
from 0.97 to 0.99,  and olivine from 0.90 to 0.98. The original 
plagioclase grains were transformed to plagioclase glass (An35 to 
An55) by an intense impact  shock, then quenched plagioclase of the 
same composition a few tens of mm up to one hundred mm in width at 
the boundaries between the  plagioclase glass and other minerals. 
Oxygen isotopic composition (T.K. Mayeda and R.N. Clayton, UChi): 
d18O == +4.46 permil, d17O ==  +2.52 permil. This meteorite was 
recovered from an area near the Dhofar 019 basaltic shergottite, but 
the two meteorites are probably  not paired. Dhofar 019 is doleritic 
and contains olivine grains with Fe/(Mg+Fe) ratios of 0.4-0.75, 
whilst these seem to be absent from  Dhofar 378. Pyroxenes in Dhofar 
019 are more magnesian than in Dhofar 378. Specimens: type specimens 
0.445 g & 0.054 g, Ibaraki; 2.74 g  MPI; main mass is with the 
anonymous finder.