Tunnel excavation produces [[rock shards]] on every action.
==== Dropshaft ====
To create a dropshaft, you need to mine a tile that is either above or below a tile that has already been dug out.
Primary uses of dropshafts are fast travel from one level of a mine to a lower level.
For example, if you dig down to water level to get a source of water, you can create a water filled cave and mine out over that cave to get a dropshaft that takes you straight down to the water.
There is no falling damage inside mines.
=== Ore mining ===