Mining

Coal rocks give Coal, caves give Iron and lakes give Water. Tap one on the map and choose Send workers. Mining is peaceful: nobody can attack your miners.

Only idle workers go: the free places in your Engine Hall's worker room. A crew has 1 to 10 workers, and each town can have 3 crews out at once. A bigger Engine Hall gives you more idle workers.

The crew walks to the spot (farther spots take longer), mines for 30 minutes and walks home. Walking makes nothing; only the 30 minutes at the spot do. A full crew of 10 mines about as much as one level 8 field: more than your low fields, less than fields at level 9 and up.

Miners keep eating Food, like every worker. Their places in the Engine Hall stay taken until they are back, so a building that needs those workers waits.

You can call a crew back at any time. On the way there, it turns round and brings nothing. While mining, it comes home with what it has mined so far.

Now and then (1 in 100 full shifts) miners strike it lucky: they bring three times the haul and some Gears.