It’s not a natural, but rather a residual lake, appeared in an old copper mine in Butte, Montana, USA. Formed at a depth of 270 meters, the water has an acidity that has not yet been matched on Earth. Heavy metals, extremely hazardous chemicals (arsenic, zinc, cadmium, zinc), not to mention the sulfuric acid, all forming a lethal “soup” for any life form. What is even more serious is that the level of acidity is increasing steadily since 1982.
