Jiddat al Harasis 054

Oman

Found 2004, January, 15

Achondrite (ureilite)

52 pieces of meteorite with total weight of 5079 g were found on January 2004 in the desert of Oman. Fusion crust is dark brown and partly preserved. Mineralogy and classification (C. Lorenz, Vernad; F. Brandstaetter, NHMW): The rock has medium-to coarse-grained granular metamorphic texture. Few large inclusions of silicates are presented in the groundmass. Main phases are olivine (Fo₈₆; 0.2-0.7 wt.% Cr₂O₃, 0.18 wt.% CaO) and pigeonite En₈₃Wo₅ (0.9-1.2 wt.% Cr₂O₃). Large grains of pyroxene contain of feldspatic glass inclusions (Ab₅₈An₄₀) and minor augite (En₅₉Wo₃₁). Accessories are chromite, Fe-metal, Ni-Cr-rich troilite (3.9-6.7 wt.% Ni; 6.7-7.3 wt.% Cr) and Ni-poor troilite (0.7 wt.% Ni; 4.1 wt.% Cr). Troilite and orthopyroxene form the fine-grained intergrowth within olivine along thin fractures, filled by iron hydroxides with troilite relics. Aggregates, 100-800 m in size, composed by graphite and diamond grains, occur between silicate grains. Total amount of carbon material is 2.8 vol.%. Silicates have thin MgO-rich rims with tiny metal inclusions along the margins of graphite-diamond assemblyes. Specimens: type specimen, 640 g, one thin and two polished sections, Vernad; main mass with anonymous finder.