Lunar meteorite (feldspathic breccia)
History: An 86.1g stone was found in the desert.
Physical characteristics: The stone lacks a fusion crust and shows fractures on the surface. The interior is rich in angular or slightly rounded clasts (to 1 cm). Some clasts are dark gray, a few are white, and the matrix is stained red by hematite.
Petrography: (S. Seddio and B. Jolliff, WUSL) A polished 18.1 mm by 8.75 mm section reveals rounded or subrounded lithic clasts of very fine grained, glassy matrix impact-melt breccia and poikilitic melt breccia fragments plus mineral clasts, welded together to form a well-consolidated, clast-rich breccia. Lithic clasts range from feldspathic, aphanitic, glassy-matrix breccias to somewhat more mafic granulitic clasts in which poikiloblastic pyroxene encloses plagioclase grains. Such clasts are abundant and typically contain partially resorbed magnesian (~Fo75) olivine grains. Plagioclase mineral clasts and grains in lithic clasts are partially converted to maskelynite and are coarsely fractured where crystalline. Fine feldspathic glass veins transect some clasts. Lithic clasts and mineral grains contain fractures, but fractures tend to be healed and closed at grain boundaries. Some of the larger fractures have been filled with terrestrial calcite, celestite, and Fe-oxide or Fe-oxyhydroxide, especially near Fe-Ni metal grains.
Geochemistry: The most abundant minerals include plagioclase (An87.2-98.6Ab1.4-8.9Or<0.1-4.3), low-Ca pyroxene (En64.1-77.0Fs17.6-33.3Wo2.6-11.2, Fe/Mn=41-70), high-Ca pyroxene (En34.8-49.9Fs13.2-30.5Wo34.7-38.8, Fe/Mn=50-70), and olivine (Fo64.2-75.9, Fe/Mn=76-118). Fe-Ni metal, troilite, merrillite, and poikilitic ilmenite surround crystals of plagioclase and pyroxene. Most Fe-Ni metal grains (up to 1-mm in size) are rimmed by iron oxide/oxyhydroxide.
Bulk composition: (R. Korotev, WUSL): 0.54% Na2O; 5.8% FeO, 530 ppm Ni, 1000 ppm Sr, 7.8 ppm Sm, 2.7 ppm Th.
Classification: Achondrite (lunar clast-rich melt breccia).
Specimens: 17.2 g is on deposit at WUSL. The main mass is held by the anonymous finder.
Classification: Lunar meteorite (feldspathic breccia)
History: Found during a foot search.
Physical characteristics: Six stones with masses of 5.8, 5.5, 4.9, 3.2, 3.2, and 0.9 g and ~2.5 to 1.5 cm in maximum size. Two stones contain significant dark, speckled fusion crust that cover most of one face of the respective stones. Shapes are angular to sub-rounded and colors range from grey, reddish, and tan with dark, sub-mm veins that connect melt pods. A 1.2-g slice of the 5.5-g stone shows a well consolidated rock with a brecciated texture of angular clasts that exhibit orange staining, and a few that are light colored. These clasts are set in a very fine-grained, gray groundmass that accounts for ~20 vol% of the sample.
Petrography: (A. Wittmann, WUSL) A 23.3 by 15.9 mm petrographic thin section exhibits a well consolidated, crystalline, melt rock that contains abundant angular, dark, aphanitic clasts, and light, angular to sub-rounded clasts that display rusty, orange staining. The complex, clast-rich, intergranular melt rock has a groundmass of 10 µm feldspar, olivine, and pyroxene, plus minor merrillite, FeNi metal, and troilite grains. Monomineralic clasts include <1 mm plagioclase, olivine, pyroxene, and spherical FeNi metal grains that are variably deformed and partly assimilated. Polymineralic clasts include dark, microcrystalline, intergranular lithic clasts that contain up to 100 µm mineral clasts of plagioclase; medium to fine-grained poikilitic lithic clasts with noritic and anorthositic mineralogies; medium-grained anorthositic clasts with granulitic textures; medium-grained anorthositic cumulate clasts of >0.3 mm feldspar with interstitial, poikilitic pyroxene and FeNi metal particles; and medium to fine-grained sub-ophitic domains of feldspar laths, zoned pigeonite, rhyolitic mesostasis, armalcolite, troilite, and FeNi metal intergrown with schreibersite. Silicate minerals frequently show reduced birefringence and intense brittle deformation. Many olivine and magnesian pyroxene clasts are extensively altered to phyllosilicates, and plagioclase shows orange staining in places. Other common alteration phases are SrSO4, CaSO4, CaCO3, and Fe-oxides that fill fractures; Fe-oxides also replace metal and troilite.
Geochemistry: Mineral compositions and geochemistry: (A. Wittmann, P. Carpenter, WUSL) Feldspar (Ab2.7-14.6An84-97Or0.1-1.9; n=21) is the most abundant component, followed by pyroxene that is mainly pigeonite (En61-75Fs20-31Wo5-14; Fe/Mn = 38-75; n=18), minor augite (En76-79Fs46-50Wo36-39; Fe/Mn = 41-48; n=3), and rare low-Ca pyroxene (En75-76Fs20-21Wo4.3-4.5; Fe/Mn = 55-58; n=2), and olivine that is mainly magnesian (Fo71-74; n=16; Fo66; n=1; Fe/Mn = 74-119). Minor components are rhyolitic mesostasis (SiO2 = 70%, K2O = 4%), Fe-Mg armalcolite (n=2) with 0.17% ZrO2, FeNi-metal (Ni = 4.4-5.9%, Co = 0.28±0.56%, n=5) and is in some cases associated with minor troilite and schreibersite (P = 12.6%, Ni = 10.6-14%, Co = 0.24-0.36%; n=2).
Bulk composition: (INAA, R. Korotev, WUSL): Na2O = 0.56, FeO = 5.8 (both in %), Ni = 475, Sr = 800, Sm = 7.3, and Th = 2.5 (all in ppm). Overall, indistinguishable from Dhofar 1627.
Classification: lunar (feldspathic breccia).
Specimens: Type specimen, ASU; TS and INAA samples at WUSL.
Dhofar 2101 (Dho 2101)
Classification: Lunar meteorite
History: The meteorite was found in 2016 during a field trip in the Oman desert.
Physical characteristics: Flattened brownish stone without fusion crust.
Petrography: (Ansgar Greshake, MNB) The meteorite is a feldspathic breccia composed of mineral fragments and basaltic clasts in a fine-grained groundmass. Most abundant minerals are calcic plagioclase and pigeonite; less abundant are augite and Fe-rich olivine. Accessories include FeS, ilmenite, and chromite. The meteorite contains calcite-filled veins due to terrestrial alteration.
Geochemistry: olivine: Fa43.1±3.5 (Fa34.9-45.7, FeO/MnO=105±12, n=20); pigeonite: Fs32.9±2.4Wo10.5±2.6 (Fs28.7-36.5Wo6.1-15.8, FeO/MnO=59±6, n=20); Ca-pyroxene: Fs20.2±2.1Wo35.0±3.9 (Fs16.1-23.8Wo27.9-41.0, FeO/MnO=54±8, n=11); calcic plagioclase: An96.5±0.5 (An95.4-97.0, n=13).
Classification: Lunar feldspathic breccia.
Dhofar 1627 and Dhofar 1980, found 8 m apart, are relatively rich in incompatibles elements for a feldspathic lunar meteorite and overall similar in composition to soils from Apollo 16. The stones are unquestionably paired. I have not studied Dhofar 2101. It was found 10 km from Dhofar 1627/1980, so it may also be a stone of the pair group. The petrographic description does not suggest pairing, however, but the photos above appear similar to me. In the absence of evidence to the contrary, I assume that Dhofar 2101 ia paired with Dhofar 1627/1980.
Meteoritical Bulletin Database
Korotev R. L. (2012) Lunar meteorites from Oman. Meteoritics & Planetary Science 47, 1365-1402.
Korotev R. L. (2017) Update (2012–2017) on lunar meteorites from Oman. Meteoritics & Planetary Science 52, 1251-1256.
Korotev R. L. (2013) Siderophile elements in brecciated lunar meteorites. 44th Lunar and Planetary Science Conference, abstract no. 1028.
Korotev R. L., Irving A. J., and Bunch T. E. (2012) Keeping Up With the Lunar Meteorites – 2012. 43rd Lunar and Planetary Science Conference, abstract no. 1152.