According to the 'Lunar Sourcebook' published in 1991 by Cambridge University Press, no silver or diamonds have been discovered in the moon rocks collected by Apollo astronauts, but gold has been found at about a few nanograms per gram of rock. It is believed this is all deposited by meteorites because the element/isotope abundance of this gold compared to iridium is the same as what is found in many terrestrial meteorites.

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