|from The Meteoritical Bulletin, No. 81 |
Dar al Gani 262
Al Juhfra, Libya
Lunar (anorthositic breccia)
History: A single 513 g stone was found in the Sahara.
Classification and description (A. Bischoff and D. Weber, Mün): contains clasts up to 1 cm, mainly anorthositic lithologies and crystalline impact melt breccias, and glass fragments and spherules (partially devitrified) imbedded in a fine-grained, well-consolidated matrix; bulk plagioclase: An>95; olivine, Fa20-71; low-Ca pyroxene, Fs26-63; has shock veins; contains metal particles (5-26 wt% Ni), ilmenite, troilite, Ti-Cr-spinel; meteorite is moderately weathered. See Bischoff and Weber (1997) for additional information.
Specimens: type specimen several grams plus two thin sections, Mün; main mass with finder.
Dar al Gani 996
Lunar meteorite (fragmental breccia)
History: Single stone of 12.31 g found by an anonymous finder in the sand desert of Dar al Gani.
Classification and mineralogy (A. Greshake, MNB; M. Kurz, Kurz): a fragmental breccia with lithic and mineral fragments set into a fine-grained clastic matrix; the clast size is generally =1 mm; mafic clasts are by far more abundant than feldspathic clasts; schlieren and vesicles are rare. Plagioclase composition, An96.7 (range An94.3-98.3); pigeonite, Fs19.7-51.3 Wo5.5-14.1; augite, Fs24.7-38.7 Wo24.7-41.7; most Ca-pyroxenes contain pigeonite exsolution lamellae; olivine, Fa30.5 (range Fa14.2-43.2). Orthopyroxene, Fe,Ni metal, ilmenite, Mg-Al-chromite, and troilite are present as minor phases; crystalline fragments include intersertal impact melt rocks, dark fine-grained and microporphyritic impact melt clasts, olivine, pyroxene and cataclastic feldspar; no regolith component, i.e. glass spherules was found; very strong mosaicism of plagioclase, as well as abundant melt veins and melt pockets attest a high degree of shock; the meteorite is moderately weathered; calcite occurs in cracks.
Specimens: main mass with anonymous finder; type specimen, 2.5 g, plus one polished thin section, MNB.
Dar al Gani 1042
Dar al Gani region, Al Jufrah, Libya
Achondrite (lunar, feldspathic regolith breccia)
History and physical characteristics: A single stone of 801 g with partial fusion crust was found in 1999.
Petrography and mineral compositions: (T. Arai, NIPR) Feldspathic regolith breccia with typical lunar highland breccia clasts (e.g., feldspathic crystalline melt breccias, granulitic lithologies, cataclastic anorthosites, etc.) embedded in a well-lithified matrix. Granulitic clasts consist of dominant plagioclase (An95.4–96.7) with orthopyroxene (Wo3Fs19En78, Fe# = 0.19), clinopyroxene (Wo8–12 Fs26–28 En62–64, Fe# = 0.28–0.30; Wo44Fs9En47, Fe# = 0.15–0.16), olivine (Fo65–69,81–84), ilmenite, and Ti-rich chromite (Chr45Hc19Usp36). Isolated mineral fragments are plagioclase, co-existing augite and pigeonite, and olivine with ranges of compositions similar to those in the above clasts. Anorthositic impact glasses occur both as glass veins and spherules. The FeO/MnO value of olivines (90 ± 20) supports a lunar origin. Terrestrial calcite pervasively occur along cracks.
Classification: Achondrite (lunar feldspathic regolith breccia); moderate weathering.
Type specimen: One specimen of 37 g is on deposit at JAXA. One 6.1 g sample and thin sections are on deposit at NIPR. An anonymous finder holds the main mass.
| from The Meteoritical Bulletin, No. 92 |
Dar al Gani 1048
Achondrite (lunar, feldspathic breccia)
History and physical characteristics: A tiny complete individual stone was reovered by an anonymous hunter in June 2001 and purchased by N. Classen in 2003 in Vienna, Austria.
Physical characteristics: A single 0.801 g medium grey stone with some diffuse whitish clasts. About 70% of the stone is covered by fusion crust.
Petrography and mineral compositions: (A. Irving and S. Kuehner, UWS) Predominantly, very fine-grained mineral debris with some larger lithic clasts (up to 0.3 mm) and vesicular glassy matrix and veins. Minerals identified include pyroxene, plagioclase, olivine, ilmenite, kamacite and troilite. Lithic clasts include gabbro (composed of plagioclase and pigeonite) and very fine grained, ophitic-textured basalt (composed of plagioclase and olivine with accessory orthopyroxene, troilite, metal and rutile). Several glassy spheres were found.
Geochemistry: Olivine (Fa19.6-49.6, FeO/MnO = 93-98), pigeonite (Fs20.2-61.9 Wo5.3-7.2, FeO/MnO = 54.8-66.5), plagioclase (An97-98Or0).
Classification: Achondrite (lunar, feldspathic breccia). This stone likely is paired with Dar al Gani 262 and Dar al Gani 996.
Type specimen: A total of 0.33 g of sample is on deposit at UWS. Classen holds the main mass.
Randy Says…Dar al Gani 262 is the first lunar meteorite to have been found and recognized from northern Africa, in 1997. Compositionally, the DaG 262 clan is a typical feldspathic lunar meteorite.
Meteoritical Bulletin Database
Bischoff A. and Weber D. (1997) Dar al Gani 262: The first lunar meteorite from the Sahara. Meteoritics & Planetary Science 32, A13-A14.
Bischoff A., Weber D., Clayton R. N., Faestermann T., Franchi I. A., Herpers U., Knie K., Korschinek G., Kubik P. W., Mayeda T. K., Merchel S., Michel R., Neumann S., Palme H., Pillinger C. T., Schultz L., Sexton A. S., Spettel B., Verchovsky A. B., Weber H. W., Weckwerth G., and Wolf D. (1988) Petrology, chemistry, and isotopic compositions of the lunar highland regolith breccia Dar al Gani 262. Meteoritics & Planetary Science 33, 1243-1257.
Cahill J. T., Floss C., Anand M., Taylor L. A., Nazarov M. A., and Cohen B. A. (2004) Petrogenesis of lunar highlands meteorites: Dhofar 025, Dhofar 081, Dar al Gani 262, and Dar al Gani 400. Meteoritics & Planetary Science 39, 503-530.
Cohen B. A., Swindle T. D., and Kring D. A. (2000) Support for the lunar cataclysm hypothesis from lunar meteorite impact melt ages. Science 290, 1754-1756.
Cohen B. A., Swindle T. D., Kring D. A., and Olson E. K. (2005) Geochemistry and 40Ar-39Ar geochronology of impact-melt clasts in lunar meteorites Dar al Gani 262 and Calcalong Creek. Lunar and Planetary Science XXXVI, abstract no. 1481, 36th Lunar and Planetary Science Conference.
Cohen B. A., Swindle T. D., and Kring D. A. (2005) Geochemistry and 40Ar-39Ar geochronology of impact-melt clasts in feldspathic lunar meteorites: Implications for lunar bombardment history. Meteoritics & Planetary Science 40, 755-777.
Fernandes V. A., Burgess R., and Turner G. (2000) Laser argon-40-argon-39 age studies of Dar al Gani 262 lunar meteorite. Meteoritics & Planetary Science 35, 1355-1364.
Fritz J. (2012) Impact ejection of lunar meteorites and the age of Giordano Bruno. Icarus 221, 1183-1186.
Jolliff B., Korotev R., and Arnold S. (2000) Electron microprobe analyses of Dar al Gani 262 lunar meteorite, a sample of the Feldspathic Highlands Terrane of the Moon. Lunar and Planetary Science XXX, abstract no. 2000.
Korotev R. L. (2005) Lunar geochemistry as told by lunar meteorites. Chemie der Erde 65, 297-346.
Korotev R. L. (2006) New geochemical data for a some poorly characterized lunar meteorites. Lunar and Planetary Science XXVII, abstract no. 1404.
Korotev R. L. and Irving A. J. (2021) Lunar meteorites from northern Africa. Meteoritics & Planetary Science, 206–240.
Korotev R. L., Jolliff B. L., Zeigler R. A., Gillis J. J., and Haskin L. A. (2003) Feldspathic lunar meteorites and their implications for compositional remote sensing of the lunar surface and the composition of the lunar crust. Geochimica et Cosmochimica Acta 67, 4895-4923.
Korotev R. L., Irving A. J., and Bunch T. E. (2008) Keeping up with the lunar meteorites – 2008. Lunar and Planetary Science XXXIX, abstract no. 1209, 39th Lunar and Planetary Science Conference.
Nishiizumi K. (2003) Exposure histories of lunar meteorites. Evolution of Solar System Materials: A New Perspective from Antarctic Meteorites, 104.
Nishiizumi K., Caffee M. W., and Jull A. J. T. (1998) Exposure histories of Dar al Gani 262 lunar meteorites. Lunar and Planetary Science XXIX, abstract no. 1957.
Schlüter J., Schultz L., Thiedig F., Al-Mahdi B. O., and Abu Aghreb A. E. (2002) The Dar al Gani meteorite field (Libyan Sahara): Geological setting, pairing of meteorites, and recovery density. Meteoritics & Planetary Science 37, 1079-1093.
Warren P. H., Ulff-Møller F., and Kallemeyn G. W. (2005) “New” lunar meteorites: Impact melt and regolith breccias and large-scale heterogeneities of the upper lunar crust. Meteoritics & Planetary Science 40, 989-1014.
Wolf S. F., Wang M.S., and Lipschutz M. E. (2009) Labile trace elements in basaltic achondrites: Can they distinguish between meteorites from the Moon, Mars, and V-type asteroids? Meteoritics & Planetary Science 44, 891–903.