Dhofar 1285        19°18′15′′N, 54°33′3′′E

Oman

Find: 11 December 2002

Achondrite (ureilite)

History: Three dark brown stones, broken into fragments of total weight 406 g, were found on 11 December 2002 in the desert of Oman. The fragments were separated by ~2.5 km.

Petrography: (Lorenz, Vernad; Brandstätter, NHMV) A coarse-grained rock that consists mainly of olivine with minor amounts of pyroxene. The veins of troilite and Fe,Ni metal crosscut the whole rock. Accessory phases, graphite, and daubreelite are present.

Geochemistry: The cores of olivine grains (Fo_76.6; Fe/Mn = 59) are surrounded by reduction rims (~50 µm in width), which contain small Fe-rich metal grains. The composition of olivine within the reduction rims gradually changes from Fo₇₈; Fe/Mn = 51 on the inside towards Fo₉₆; Fe/Mn = 8.6 at the outer edge. The outer parts of the olivine grain rims are completely replaced by a fine-grained aggregate of olivine (Fo_97–99), troilite, and metal. Reduction zones are developed along cracks and veins that cross-cut olivine grains. Pyroxene (En_78.7Wo_9.8; Fe/Mn = 20) contains numerous, tiny, co-oriented inclusions of Ca-rich pyroxene (En_56.2Wo_37.3; Fe/Mn = 13), SiO₂-rich feldspathic (Ab₅₀An_48.5) glass, low-Ni Fe,Ni metal grains, and extremely fine, poorly resolvable exsolution lamellae of Ca pyroxene. In places, pyroxene grains also have reduction rims with composition En₈₃Wo_6.7. Cr₂O₃ contents of olivine and pyroxene (0.7 and 1.1 wt% respectively) and CaO content of olivine = 0.4 wt% are in the ranges of those established for ureilites.

Classification: Achondrite (ureilite); moderate shock, extensive weathering.

Specimens: A 92.48 g type specimen and one thin section are on deposit at Vernad. An anonymous finder holds the main mass.