Ключевые слова: background, black, black background, black gold, board, bucket, carbon, carbon dioxide, charcoal, coal, coal pile, coal structure, combustible, dark, deposits, dust filter, dust mask, energy, energy source, energy storage, exploitation, extraction, filter mask, fossil, fossil fuel, fuel, gas mask, hammer, hard, industrial, industry, lump, metal bucket, metal buckle, mine, mineral, mining, night, pickaxe, pollution, potential, raw material, shale, solid fuel, stone, to be burned, unclean, underground, wealth, wooden box,