Study physical and chemical methods to extract valuable things from dirt or from the air. Needless to say these methods need to be economical, in the end.

This is motivated by the fact that dirt is very cheap, and contain many interesting elements, but that are somehow, not acessible to us.

It really puzzles me how everyone has access to air, but little people think about making a living by trading noble gases, por example. It is such a rare situation for you to be this close to something that is valuable.

There a whole big discussion about where to get the dirt from, too.