How to determine a good spot for a mine (T3 building)?

[Fungi]

Hi. How to find a proper spot for a mine building, so there are resources underground? I've built like 2 mines near surface resources (copper) and there was nothing or almost nothing to mine there.
Note: I mean T3 mine building, not the surface mining with a pickaxe.

[tamu1997]

There are no underground resources. Once you mine out the nodes thats it

[Ruffio]

surface rocks is all there is.

[Agent707]

I see no point in the T3 mining building. None. The T2 building can get iron, which is all you need.

[Fungi]

I meant the Pit building (sorry for the misunderstanding, I didn't know the original name of that building). Does it mine underground resources, as the building suggests (it has a crane and a shaft) or it is just the same surface nodes collector as all the T2 and T1 buildings, but with larger radius?