=== Opening a mine ===
The first step in all mines is to make a mine entrance on the surface. This can be done on any [[cliff]] or [[rocktile]] tile. Equip a mining pick, and select the "Tunnel" option. After 51 tunneling actions, the message "You will soon create an entrance" will appear. A few actions later an entrance will be created. The exact value is random, averaging around 5 mining actions after the message appears.
Tunneling on a shallow [[slope]] is dangerous since you are basically mining straight down and may dig yourself into a steep slope or a pit. A slope of 10+ is probably safe (estimate). The good news is that a poor tunnel slopes can be fixed. The bad news is that it is a lot of work!