Carbon on the Moon

The only carbon Apollo rock scientists have found is the trace put there by eons of buffeting of the surface by the solar wind - the atoms and ions from the wind are adsorbed to the surface of the fine particles of the regolith. It is a trace only to be found in the upper meter or two, where it amounts to 82 parts per million. It can be harvested by picking up, then heating the surface deposits to 600 or 700 degrees Fahrenheit. If we ever did extensive helium-3 mining in similar fashion, solar wind-derived carbon, nitrogen, and hydrogen, along with garden variety helium, would be economically important by-products.

As to "Sudbury"-like impact donated lodes of various elements, impacting nickle iron bodies do have a slim chance of remaining intact, and hence minable. It will be a major goal of future prospecting to find such lodes for the otherwise scarce elements they may contain such as copper, zinc, etc. But carbonaceous chondrite asteroids are so structurally weak that there is very little chance of any core surviving. Most likely they will vaporize on impact, and any carbon monoxide or dioxide or other volatilizable compounds they contain will then have some slim chance of migrating to polar permashade cold traps to get frozen out along with water ice - before the solar wind blows them off into space. Thus it would be better to look for impact-derived carbon in any yet-to-be-confirmed polar ice deposits than elsewhere. There is a very slim chance that a comet or carbonaceous chondrite could have impacted through the roof of an otherwise intact lava tube and some portion of the volatiles frozen out on the sides of the tube rather than escaping out the impact hole. If that has happened, it will be the equivalent of the moon winning the cosmic lottery.

The moon, even though it is 45% oxygen, is actually underoxidized. This is clear from the fact that the soil contains a high percentage of free iron (unoxidized) powder fines (harvestable for the price of a magnet), and that what oxidized iron (ore) there is is ferrous (FeO), not ferric (Fe2O3). How does this affect the carbon question? On Earth, carbon dioxide is the main ingredient of volcanic gasses. On the Moon, we would not expect that. If there were any carbon oxide volcanic emissions at all, we'd expect them to be monoxides. There is no good reason or strand of evidence to suspect any internal carbon at all, however. One of the important searches no one in NASA has yet proposed is to analyze the chemical makeup of the so called Transient Lunar Phenomena (TLPs) or fleeting glows that appear here and there on the surface, from time to time, clustering in certain areas. These could be gas belching up through fissures and cracks in the surface. Radon is most likely, but CO would be far more useful economically.

If we detected CO burps, it would mean pockets of CO gas under pressure trapped under unfractured crust deep below. These would be as economically significant a find as polar ice fields. But don't count on it.

On the whole, the moon is far more chemically and mineralogically homogeneous than the Earth and what the Apollo missions sampled should be pretty representative - with very rare (but economically potentially significant) exceptions.