Ключевые слова: acid, background, chemical, chemistry, crater, dig, earth, energy, environment, excavation, fossil, fumes, gas, geology, heap, heat, ijen, indonesia, industry, java, kawah, lake, material, mine, mineral, mountain, nature, open, ore, pit, poisonous, power, raw, resource, rock, site, smoke, steam, stone, strip, sulfur, surface, white, worker, yellow,