Lunar Meteorite Shisr 166
Lunar Meteorite Shisr 166 See Randy Korotev web page: http://meteorites.wustl.edu/lunar/stones/shisr166.htm Shişr, Oman Find: April 10, 2008 Achondrite (lunar, feldspathic impact-melt breccia) History: One stone was found by Luc Labenne in the desert at night. Physical characteristics: The 128.8-g meteorite lacks an obvious fusion crust. The interior consists of a gray, vesicular (up to 1.2 mm vesicles) melt matrix with rounded clasts stained red by hematite. Many vesicles are filled with terrestrial alteration products, including calcite, Ca-sulfate, and celestite. Petrography: (R. Zeigler, WUSL) Melt matrix dominated by plagioclase (average: An96.7Or0.2) with intergrown of pigeonite (average FsxxWoxx; Fe/Mn = 57), augite (FsxxWoxx; Fe/Mn = 48), and olivine (Fo61; Fe/Mn = 102) in an apparent poikilitic texture. Also present within the matrix are small grains of troilite, Cr,Ti,Fe spinel (19 wt% TiO2, 25 wt% Cr2O3 , 23 wt% FeO), and ilmenite (5 wt% MgO, 1.5 wt% Cr2O3), the latter two often intergrown. There are a few plagioclase clasts (typically 0.2 mm, up to ~1 mm) and a few smaller olivine and pyroxene clasts. Large veins of partially devitrified shock melt occur. Average composition of the shock-melt vein: 43.7% SiO2, 0.24% TiO2, 29.7% Al2O3, 4.3% FeO, 0.07% MnO (Fe/Mn = 63), 4.0% MgO (Mg´ = 63), 16.8% CaO, 0.32 wt% Na2O, and 0.03 wt% K2O. Bulk Chemistry: (R. Korotev, WUSL): 0.32% Na2O, 4.1% FeO, 7.9 ppm Sc, 140 ppm Ni, 1.2 ppm Sm, 0.74 ppm Eu, 0.42 ppm Th. The meteorite differs in composition and texture from Shişr 160, 161, and 162. Classification: Achondrite (lunar, impact-melt breccia). Type Specimen: 20.1 g are on deposit at WUSL, the main mass is held by Mr. Luc Labenne.