Lunar Meteorite: Dhofar 733 & 1766

Dhofar 733

Oman
Found: 2002 November 12
Mass: 98 g (1 piece)

Classification: Lunar meteorite (anorthositic granulitic breccia)

History: A brownish grey stone weighing 98 g was found in the Dhofar region of Oman.

Mineralogy and classification (S. Demidova, Vernad; G. Kurat, MNHV): fusion crust is absent; the rock contains relics of mineral and lithic clasts and shows granoblastic or poikiloblastic textures; anorthositic, troctolitic and gabbro-noritic lithologies are present.

Mineral compositions: feldspar, An_89-96; orthopyroxene, Wo_4-5E_73-76; clinopyroxene, Wo_36-40, En_48-52; olivine, Fo_71-76 (Fe/Mn ~87 at). Accessory minerals are armalcolite, ilmenite, Al-Chromite, Ca-phosphate, troilite, and FeNi metal (31-43 wt% Ni; 1.3-1.7 wt% Co); lath-shaped armalcolite is most common; the stone is moderately weathered; smectite, gypsum, and Fe hydroxides are present. Dho 733 was found far away from other lunar stones collected in the Dhofar region and has a distinctly different texture. It is probably not paired with any other Dhofar lunar finds known so far.

Dhofar 1766

Zufar, Oman
found: 2011 December 9
Mass: 292 g (1 piece)

Classification: Lunar meteorite (feldspathic breccia)

History: Found by a prospector in December 2011.

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: (A. Wittmann and P. Carpenter, WUSL) 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 tetrataenite 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: (A. Wittmann, WUSL): Plagioclase (An_77-96Ab_13.9-3.4Or_0-0.7; N=21); olivine (Fa_10-30, molar Fe/Mn=61-195; N=20); augite (Fs_10-21Wo_24-42, molar Fe/Mn=34-40; N=3); armalcolite (up to 0.4 wt% ZrO₂; n=6); spinel (Mg_3.65–4.84Al_6.48–12.77Fe_3.24–4.57Ti_0.37–0.65Cr_2.57–8.44O₃₂ ; 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.

Classification: Lunar (feldspathic melt rock).

Specimens: 20.3 g of type material and one polished thin section are at UWB. The remaining material is held by the anonymous finder.

Randy Says…

Compositionally, Dhofar 733 and Dhofar 1766 are distinct in having concentrations of Na and Eu about twice that typical of other feldspathic lunar meteorites as a result of more albitic plagioclase. Because they are compositionally similar to each other and were found in proximity to each other, I suspect that they are paired despite the textural differences.

More Information

Meteoritical Bulletin Database

Dhofar 733 | 1766

Map

Schematic Map of  Find Locations of  Lunar Meteorite from Oman

References

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