Lunar Rocks in Antarctica

The number of lunar meteorites (also called luna-ites by Warren et al. 2005) has increased from one in 1981 to 32 in 2005, including the 22 specimens in 

Appendix 18.12.3 recovered in Antarctica (Zeigler et al. 2005). Several specimens are paired because they are either fragments of a lunar rock sample that broke up during its passage through the atmosphere or because they originated from the same impact crater on the Moon (i.e., source pairing, Warren 2005). 

The lunar meteorites have aerodynamically rounded shapes and are covered by a fusion crust which they acquired while they passed through the atmosphere of the Earth. Lunar meteorites also contain cosmogenic radionuclides (e.g., °Be, Al, Cl, and Mn) because they were exposed to cosmic rays on the surface of the Moon and while they were in transit from the Moon to the Earth. Many lunar meteorites are breccias and contain evidence of shock metamorphism. Like the other nonchondrites in Table 18.1, the lunar meteorites lack chondrules and do not contain grains of metallic Fe-Ni alloys. Because of their similarities to achondrite meteorites and to pebbles or cobbles of terrestrial rocks, lunar meteorites are not easy to identify in the field and, in some cases, were only collected in response to the ANSMET imperative When in doubt, collect... . 

The chemical composition of ALHA 81005 in Table 18.10 was determined by Korotev et al. (1983) who used the method of instrumental neutron-activation analysis (INAA) because it is nondestructive, because it is well suited for the analysis of small samples, and because it can determine many elements simultaneously. For example, Korotev et al. (1983) analyzed seven small grains of the meteorite with a total weight of only 78 mg and obtained the concentrations of 33 elements from each of these granules. The final result in Table 18.10 

Oxide Cone. (%) Element Cone. (ppm) Element Cone. (ppm) 

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