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Lunar Meteorite

Dhofar 733 & 1766
(paired stones)

Oman

 

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Dhofar 733 in the field

(photo credit: anonymous finder)

 

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A very small block of Dhofar 733

(photo credit: Randy Korotev)

 

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Dhofar 1766 in the field

(photo credit: anonymous finder)

 

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lm_dhofar_1766_0465m.jpg

Sawn faces of 2 slices of Dhofar 1766. Millimeter ticks for scale. The lightest-colored regions are vesicles filled with terrestrial alteration minerals like gypsum and celestite. Click on image for enlargement.

(photo credit: Randy Korotev)

 

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lm_dhofar_un38b_5105m_12mm.jpg

Images of a thick (100 m, top) and thin (35m, bottom) section of Dhofar 1766.
Maximum width: 12 mm.

(photo credit: Randy Korotev)

 

from The Meteoritical Bulletin, No. 87, Meteoritics & Planetary Science 38, A189A248 (2003)

Dhofar 733 

Oman 
Found: 2002 November 12
Mass: 98 g

Lunar meteorite (anorthositic granulitic breccia) 

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, An89-96; orthopyroxene, Wo4-5En73-76; clinopyroxene, Wo36-40En48-52; olivine, Fo71-76 (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.

Specimens: type specimens of 20 g, and a thin section, Vernad; main mass with anonymous finder.

 

from The Meteoritical Bulletin, No. 102

Dhofar 1766

Zufar, Oman
Found: 2011 December 9
Mass: 292 g

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 m skeletal pyroxene crystals filling interstices. Olivine occurs up to 50 m, 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 m armalcolite crystals. Accessory troilite occurs in the melt groundmass as round to oval, <10 m crystals, some of which are intergrown with minute taenite and tetratenite grains; subhedral to granular, 30 to 250 m 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 (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 (Mg3.654.84Al6.4812.77Fe3.244.57Ti0.370.65Cr2.578.44O32 ; 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 the Find Locations of the Dhofar Lunar Meteorites

References

Demidova S. I., Nazarov M. A., Lorenz C. A., Kurat G., Brandsttter F., and Ntaflos Th. (2007) Chemical composition of lunar meteorites and the lunar crust. Petrology 15 (4), 386-407.

Foreman A. B., Korotev R. L., Jolliff B. L., and Zeigler R. A. (2008) Petrography and geochemistry of Dhofar 733 An unusually sodic, feldspathic lunar meteorite (abstract). In Lunar and Planetary Science XXXIX, abstract no. 1853, 39th Lunar and Planetary Science Conference.

Korochantseva E. V., Buikin A. I., Hopp J., Korochantsev A. V., and Trieloff M. (2016) 40Ar-39Ar results of lunar meteorites Dhofar 025, 280, 309, 730, 733, 1436, 1442, SaU 449, NWA 6888 (abstract). 79th Annual Meeting of the Meteoritical Society, abstract no. 6317.

Korotev R. L. (2005) Lunar geochemistry as told by lunar meteorites. Chemie der Erde 65, 297-346.

Korotev R. L. (2012) Lunar meteorites from Oman. Meteoritics & Planetary Science 47, 13651402. doi: 10.1111/j.1945-5100.2012.01393.x

Korotev R. L. (2017) Update (20122017) on lunar meteorites from Oman. Meteoritics & Planetary Science 52, 1251-1256.
All Korotev data on Omanian lunar meteorites.

Korotev R. L. and Irving A. J. (2014) Keeping up with the lunar meteorites 2014 (abstract). 45th Lunar and Planetary Science Conference, abstract no. 1405.

Shukolyukov, Y. A., Nazarov, M. A., Ott, U. (2004) Noble gases in new lunar meteorites from Oman: Irradiation history, trapped gases, and cosmic-ray exposure and K-Ar ages. Geochemistry International 42, 10011017.

Wittmann A., Korotev R. L., and Jolliff B. L. (2014) Third of a kind Impact melted lunar granulitic breccia meteorite Dhofar 1766 (abstract). 45th Lunar and Planetary Science Conference, abstract no. 1182.

 

 

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Prepared by
: Randy L. Korotev

Department of Earth and Planetary Sciences
Washington University in St. Louis

Please don't contact me about the meteorite you think you've found until you read this and this.


e-mail
korotev@wustl.edu

Last revised: 13-June-2017