abstract
background
bituminous
black
burning
carbon
charcoal
coal
cost
cube
dark
deposit
dirty
effect
energy
environment
exploitation
extract
extraction
fossil
fuel
gas
hard
heat
hot
industrial
industry
lignite
manufacturing
material
metallurgical
mine
miner
mineral
mining
pile
power
resource
rough
smoke
station
stone
stove
structure
surface
texture
textured
tiled
type
unclean