Question regarding Prospecting

[Bugssy]

Does prospecting in a cave only find minerals in the level below you? Or can a reading in a cave pick up minerals in the walls too?

That is, does prospecting look for minerals in the layer you are on and the layer below you? Or does it only pick up minerals on the layer under you?

[Mashadar]

Yes, no, no, yes (that is: only below you).
If you want to find ore in a cave without taking samples, you'll have to follow the cave's passageways on the surface and prospect there.

[Sevenless]

viewtopic.php?f=2&t=18450&hilit=prospecting

Read this as well. The system can be pretty annoying to figure out from scratch.