I am rooting for argon being released by mining on the moon and iron oxide being converted to oxygen. Thus the atmosphere would be created in the amounts necessary for life. The moon would be different from earth because the argon would have its own coloring effect. What I do not know is if argon alone would be too heavy for respiration. Of course helium could be there in a smaller amount.
We have to remember though that nitrogen is an important constituent of life so we may need substantial amounts of that also. I suppose if there were deposits of ammonia on the moon that can be converted to water and nitrogen, assuming oxygen is present. Somehow some carbon dioxide would have to be added so that plant life could thrive for photosynthesis to occur. That would take care of the carbon dioxide and oxygen cycle for animal life to respire. Knowledge of environmental chemistry would be important if I were to write a sci-fi story. I guess that is why writers like Asimov had a large knowledge base of science.
oops
I meant ammonia instead of methane – ammonia combined with oxygen would give nitrogen and water.
Methane with oxygen would give carbon dioxide and water.
I edited the mistake