Gold
Gold is one of the most valuable resources in the world. It is extremely popular, especially for jewelry and accessories. Gold mining has been done for centuries and has an extensive history, as well as many different methods from which extraction takes place.
History
Romans used large scale hydraulic mining to extract gold from widely spread alluvial deposits, like those at Las Medulas. In the nineteenth century, gold rushes took place in countries, like the United States, Australia and South Africa. A gold rush is a period in which a large number of workers migrated to an area where tons of gold was consistently being found and mined.
Panning
One of the most primitive extraction techniques, panning, is a manual technique in which the workers fill wide, shallow pans with sand and gravel that may contain gold. They then sift through the pan to see if any gold is there--this is considered the easiest forms of finding small amounts of gold.
Metal Detecting
In this technique, a metal detector is used to scan for gold. A positive reading means that gold may be present up to a meter underneath the ground surface.
Hard Rock Mining
Hard rock mining is a process for extracting gold from rock. Two hard rock mining methods are used and include open-pit mining and underground mining. These are the processes by which most of the world's gold is extracted.
Effects on the Environment
Gold mining is becoming an increasingly dirtier process as open pit mining is becoming more common due to the decline in gold deposits. The waste produced by open pit mines is eight to 10 times greater than underground mines.
Toxic Waste
Cyanide heap leaching is the least expensive method of gold extraction; therefore, it is widely used. It produces large quantities of wasted rock and leaking toxins. The leaching process takes months to complete, so it almost becomes impossible to control cyanide contamination of the surroundings. Cyanide is a deadly chemical, and exposure to high levels of it may cause a coma and death.
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