abandoned
background
catacomb
cave
cavern
cellar
coal
construction
copper
corridor
dark
deep
dig
dirt
dirty
dungeon
dust
entrance
excavate
gold
hole
industrial
industry
inside
interior
iron
lamp
light
long
material
mine
mining
narrow
old
passage
path
primary
rail
railroad
railway
resource
rock
shaft
structure
tunnel
tunneling
underground
underpass
work