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Lunar Meteorite: Shişr 161Oman |
 Exterior of Shişr 161 (centimeter cube on right) (Photo courtesy of Greg Hupé and Phil Mani)  Slices of Shişr 161 (centimeter cube on right) (Photo courtesy of Greg Hupé and Phil Mani)
 A small sample of Shişr 161 (millimeter ticks for scale) (Photo by Randy Korotev) |
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from The
Meteoritical Bulletin, no. 95, Meteoritics & Planetary Science 44,
429-462 (2009).Shişr 161Oman Find: January 2008 Achondrite (lunar, feldspathic fragmental breccia) History: One stone of 57.2 g found by Michael Farmer and later sold to Philip Mani. Physical characteristics: The meteorite lacks an obvious fusion crust but has the frosted, ablated exterior typical of Omani lunar stones. The interior is light brown with few fractures, and terrestrial weathering is negligible. Petrography (A. Foreman, WUSL; A. Irving and S. Kuehner, UWS): The meteorite is a fragmental breccia composed of a variety of lithic clasts (3–7 mm) and mineral fragments (0.3–0.4 mm) of olivine, plagioclase, augite, and pigeonite set in a fine-grained matrix with some glass veins. Lithic clasts include feldspathic granulitic breccia (plagioclase matrix with interstitial grains of granoblastic olivine), spherulitic basalt consisting of dominantly lath-shaped plagioclase and pyroxene, fragmental breccia with 0.3–0.4 mm clasts of plagioclase, olivine, augite, and pigeonite set in a fine-grained light-brown/gray matrix, and a granophyre composed of plagioclase, pigeonite, chromite, and ilmenite. No regolith components (glass spherules) have been identified. Very minor FeNi metal. Geochemistry (A. Foreman, WUSL): Feldspathic granulitic breccia: olivine (Fa20.9–37.2, FeO/MnO = 73–115), plagioclase (An94.5–97.7 Or0.0–0.3); basaltic clast: 60.0% plagioclase (An94.5–96.7 Or0.2–0.5), 34.8% orthopyroxene (Fs41.7–47.1 Wo2.5–3.9, FeO/MnO = 55.2–59.4), 3.9% augite (Fs14.9–26.6 Wo30.7–41.9, FeO/MnO = 46.3–62.5), 0.3% ilmenite, fragmental-breccia clast: plagioclase (An96.6 Or0.4), olivine (Fa35.4–39.3, FeO/MnO = 82–95), augite (Fs16.4–16.9 Wo38.9–39.8, FeO/MnO = 40.6–41.0); mineral fragments: plagioclase (An93.9–98.6 Or0.0–0.6), olivine (Fa17.4–62.5, FeO/MnO =75–101), augite (Fs10.3–51.4 Wo21.4–42.4, FeO/MnO = 29.5–88.2), pigeonite (Fs27.6–47.3 Wo8.1–19.5, FeO/MnO = 49.9–63.1). Bulk composition (R. Korotev, WUSL): FeO 5.6 wt%, Sc 13 ppm, Ni 90 ppm, Sm 0.64 ppm, Th 0.16 ppm. Classification: Achondrite (lunar, feldspathic fragmental breccia). Specimens: A total of 11.5 g is on deposit at UWS. Thin section at WUSL. The main mass is held by Mr. P. Mani. |
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