A Personal mine is a building that creates a cave system for the player to enter. Personal Mines generate a cave system where ores, gems, loot in basket and bones are found.
Personal Mines can be crafted using a Crucible.
Just like real caves, you can't define what will appear inside them.
Just as normal caves are a safe place, when you are in a battle against high-level hybrids that are higher than yours, they are the best refuge for an emergency exit.