black
black gold
board
bucket
carbon
carbon dioxide
coal
coal pile
coal structure
combustible
dark
deposits
energy
energy source
energy storage
exploitation
extraction
flashlight
fossil
fossil fuel
fuel
glow
hard
hard coal
helmet
industrial
industry
light
lump
male
metal bucket
metal clamp
mine
miner
mineral
mining
night
pollution
potential
raw material
shale
shines
solid fuel
stone
unclean
underground
wealth
wooden box
worker
working clothes