I like the concept, reminds of dome keeper, there are issues though.
Besides the obvious amount of idling, the beginning was pretty slow, then i found platinum and it boosted me immensely, i would suggest locking valuable minerals to other caves, and the idling on the start could be mitigated by adding an enemy there too. I also found a way to go out of bounds through the corners at the bottom of the caves.
Fun concept, just lacks some polish👍