Dhofar 1766
18.592°N, 54.271°E
Zufar, Oman
Found: 2011 Dec 9
Classification: Lunar meteorite (feldspathic breccia)
Physical characteristics: Angular 5 × 4 × 3 cm stone (292 g) with shiny, reddish exposure surface and bluish-grey basal surface. On surface ~5 mm rounded, knobby, yellowish-white to dark grey, partly melted clasts are embedded in a flow-textured groundmass, which has abundant, sub-mm vesicles.
Petrography:Melt rock with flow texture of aphanitic melt enclosing 5 to <0.5 mm size clasts of feldspar-rich rocks. All clasts are recrystallized but retain outlines of original textures of poikilitic to subhedral mafic silicates in plagioclase-dominated groundmass. Groundmass plagioclase forms dense masses of tabular, felty textured crystals with <10 µm skeletal pyroxene crystals filling interstices. Olivine occurs up to 50 µm, zoned, subhedral crystals in the melt groundmass, and in partly assimilated clasts is overgrown with augite that poikilitically encloses acicular plagioclase, silica-rich mesostasis and euhedral, up to 30 µm armalcolite crystals. Accessory troilite occurs in the melt groundmass as round to oval, <10 µm crystals, some of which are intergrown with minute taenite and tetratenite grains; subhedral to granular, 30 to 250 µm chromian spinel crystals exhibit variable ° of decomposition and recrystallization. Abundant vesicles are hollow or occupied by secondary gypsum, celestite, rare barite, and greenish-yellow, Mg-rich phyllosilicates (talc?) that are rimmed by celestite.
Geochemistry: Plagioclase (An77-96Ab13.9-3.4Or0-0.7; N=21); olivine (Fa10-30, molar Fe/Mn=61-195; N=20); augite (Fs10-21Wo24-42, molar Fe/Mn=34-40; N=3); armalcolite (up to 0.4 wt% ZrO2; n=6); spinel (Mg3.65–4.84Al6.48–12.77Fe3.24–4.57Ti0.37–0.65Cr2.57–8.44O32 ; n=3), troilite (up to 0.3 wt.% Ni; N=3), metal (36.5-45.5 wt% Ni, 1.3-1.4 wt% Co). Bulk composition (R. Korotev, WUSL) INAA of subsamples gave mean abundances of (in wt.%) FeO 2.9, Na2O 0.69, CaO 16, (in ppm) Sc 4.6, La 1.2, Sm 0.58, Eu 1.6, Yb 0.36, Th 0.08, and 1.1 ppb Ir.
