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Carbonaceous Chondrite (C-Type) asteroids are very common. They make up about 70% of the asteroid belt, though less closer in. One would presume that a lot of them have fallen on the moon. It occurs to me that they might be a source of carbon for lunar colonies.
The question is; has anyone found meteorites, especially C-type on the moon? This could be returned samples from Apollo or the Luna missions, or material found in place and simply identified, by other probes.
Yes, we have found evidence for carbonaceous chondrites on the Moon. Apollo 15 and 17 both brought back samples of lunar rock that had hydrogen inclusions with an isotopic ratio that exactly matches that of the water in carbonaceous chondrites. See the cite below for details.
Here's another paper from Nature on the same subject, which concludes that the bulk of magmatic water (about 300ppm of the interior magma is water, according to the evidence from the Apollo samples) came from carbonaceous chondrites, and not from comets. Considering that most of the volatiles from those impacts were likely lost to space, I would think that a residual 300ppm of water implies a significant number of impacts.
An asteroidal origin for water in the Moon
That said, none of the Apollo samples contained anything but trace amounts of carbon. The process that trapped water in the mantle from CC asteroids may not have trapped the carbon, or the carbon in the asteroids may have reacted with lunar rocks to make carbon compounds that are buried in the mantle. Another possibility for the carbon is that it leaked out over geologic time as carbon monoxide, and some of that may have migrated to permanently shadowed craters. If I wanted to find carbon on the moon, that's where I would start looking.
Unlike stony or metallic asteroids, which may have mineable cores still available near the surface, the CC asteroids likeky vaporized or at least powderized on impact. So other than the permanently shadowed craters or perhaps deep gas pockets I wouldn't expect to find concentrations of carbon on the moon.
That said, our exploration of the moon is in its infancy, and lots is subject to change as we explore further.
+1 for a very informative and well-sourced answer!
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