From Talus Wiki

>To mine, one must have a Miners Pickaxe equipped. Once equipped, all that needs to be done is to find a Minaeble Rock and double click it. After the appropriate amount of damage is done to the rock, you will chip off a nugget. There is a small chance that the player will receive a second nugget while mining. There is also a very small chance that the player will find a mystery mineral. These minerals need to be washed at the Mineral Bath to discover their type. Miners Pickaxes will wear out from time to time and the Mineable Rocks will also “dry up” (disappear). The Mineable Rocks can be set to respawn after a configurable amount of time.

---