Dhofar 378

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 the other Dhofar meteorites. Classification and description: (Y. Ikeda and M. Kimura, Ibaraki; H. Takeda, Chiba): it has a doleritic or microgabbroic texture, and the grain sizes of the main minerals (pyroxenes and plagioclase glass) are ~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 micrometer up to 100 µm in width at the boundaries between the plagioclase glass and other minerals. Oxygen isotopic composition (T. K. Mayeda and R. N. Clayton, UChi): δ₁₈O = +4.46‰, δ₁₇O = +2.52‰. 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, while these seem to be absent from Dhofar 378. Pyroxenes in Dhofar 019 are more magnesian than in Dhofar 378. Specimens: type specimens, 0.445 and 0.054 g, Ibaraki; 2.74 g MPI; main mass is with the anonymous finder.