abandoned
background
catacomb
cave
cavern
cellar
coal
construction
copper
corridor
dark
deep
dig
dirt
dirty
dungeon
dust
entrance
excavate
geology
gold
hole
industrial
industry
inside
interior
iron
light
long
material
mine
mineral
mining
narrow
nobody
old
passage
primary
rail
railway
resource
rock
shaft
stone
structure
tunnel
underground
underpass
work