Gold mining today is different than that in a couple of ways. First, open-pit gold mines are common now, where the "overburden"—the grass and trees and every other living thing above the place to be mined—is removed and the ore is blasted and scooped out. Not only do open-pit mines scar the landscape, they produce 8 to 10 times more waste than underground mining.
Another even more serious problem is the fact that gold is now rarely found as nuggets, but rather is extracted chemically from the ore by using a cyanide leaching process. Though this process is designed to be a closed system, with leach heaps and contaminated tailings isolated from their surroundings, their long timeframes and the extensiveness of the operations usually lead to cyanide and other toxics eventually getting into the surrounding land, surface water, and groundwater.
In some cases, acid mine drainage—in which the sulfides in the now-exposed rock waste combine with water to form sulfuric acid—turns groundwater more toxic than battery acid. As for cyanide, an amount of it equivalent in size to a grain of rice will kill a human, and very low concentrations of cyanide in surface water will kill fish.
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