If you own land, almost anywhere in the world, you own it from the centre of the earth to the edge of the universe.
However, there are also, almost anywhere in the world, laws that permit other people to fly aeroplanes and spaceships in your airspace, without paying rent or asking permission. It doesn't stop that space being yours, but it's pointless ownership except that you can build into it.
Under your land, you can mine it. That is easier to enforce. Anybody who wants to mine under your land, needs your permission, and you can charge for that.
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