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The Genesis Rock is a sample of Moon rock retrieved by Apollo 15 astronauts James Irwin and David Scott in 1971 during their second lunar EVA, at Spur crater. It is currently stored at the Lunar Sample Laboratory Facility in Houston, Texas. It is sample number 15415. Chemical analysis of the Genesis Rock indicated it is an anorthosite, composed mostly of a type of plagioclase feldspar known as anorthite. The rock was formed in the early stages of the solar system, at least 4 billion years ago.〔(Apollo 15 samples overview ) Lunar and Planetary Institute〕 It was recovered in a crater of the Moon, near other rocks of its kind. It was originally thought they had found a piece of the Moon's primordial crust, but later analysis initially showed that the rock was only 4.1 ± 0.1 billion years old, which is younger than the Moon itself; and was formed after the Moon's crust solidified. It is still an extremely old sample, formed during the Pre-Nectarian period of the Moon's history. Dating of pyroxenes from other lunar anorthosite samples gave a samarium-neodymium age of crystallization of 4.46 billion years.〔Norman, M. D., Borg, L. E., Nyquist, L. E., and Bogard, D. D. (2003) ''Chronology, geochemistry, and petrology of a ferroan noritic anorthosite clast from Descartes breccia 67215: Clues to the age, origin, structure, and impact history of the lunar crust,'' Meteoritics and Planetary Science, vol 38, p. 645-661 (Summary )〕 The solar system was formed only around 100 million years earlier.〔Chaikin, A., and T. Hanks. 1998. A man on the Moon : the voyages of the Apollo astronauts. Penguin Books, New York, N.Y.〕 ==See also== * Apollo 15 on the Moon * Hadley–Apennine (Moon) * Anorthosite 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Genesis Rock」の詳細全文を読む スポンサード リンク
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