| How Gold is Produced Extraction and Cyanide Leaching
- Two-thirds of all gold in use is newly mined. Of this gold, two-thirds is from open-pit mines, several of which are big enough to be seen from outer space.
- An open-pit mine generates huge piles of waste rock, which can leach toxic metals and acid into soil and wate
- Heap leaching is a common way to separate gold from ore, in which the ore is piled into heaps and sprayed with cyanide.
- Accidents involving cyanide-laced mine wastes have caused fish kills, severe water pollution, and soil contamination.
Smelting and Refining
The separated gold is shipped to a smelter where the remaining impurities are removed under intense heat. This process emits toxic air pollutants, including components of smog and acid rain. Worldwide, all metal smelting adds about 142 million tons of sulfur dioxide to the atmosphere every year -- 13 percent of total global emissions.
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