@TimberWolfAU - thanks for the Korotev reference!
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More from the Korotev article:
Quote: "We have no reason to suspect, based on data obtained from orbit that any region of the moon is rich in types of rocks significantly different from those we that know about or postulate might exist. [...] It is highly unlikely that any yet-unfound lunar meteorite will differ substantially from the Apollo lunar rocks and known lunar meteorites in the minerals it contains or in its geochemical character."
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Basically, if I was to go to the moon and collect a rock sample from the moon and send a probe up to either analyze it in situ or retrieve some more rocks for analysis, I'd expect to get the same results. Especially considering that the moon is atmosphereless and not geologically active.
…And yet, here we are. Chang'e 3 and 5 detected/retrieved rocks that differ in mineralogy.