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Please note that this article has errored by including “Dawson City, Yukon, Canada” (Klondike Gold Rush) on the list. The Klondike’s short-lived, decade-long goldrush only produced 12.5 million ounces of the precious metal. By comparison, the Porcupine Camp (Timmins, Ontario), discovered in 1909 and still in production, has produced 72-million ounces, once again booming Kirkland Lake, originally discovered in 1911, has produced 38-million ounces to date and Red Lake, originally found in 1925, has produced 26-million ounces up to 2006, and is currently experiencing another boom. Link here for: Battle of the Canadian Gold Rushes: Klondike Versus Northern Ontario. – Stan Sudol/RepublicofMining.com
The World’s 10 Most Prolific Gold Fields
Gold has long been one of mankind’s most prized possessions. Yet most people have little idea where gold comes from, other than from “gold mines.”
Mining gold today often becomes monumental undertakings, truly some of man’s greatest engineering feats. Imagine gold mining shafts nearly two and a half miles below the surface and it taking two hours for miners to get to their work stations. Imagine a pit so large that it can be seen from outer space.
No reason to imagine, those are the realities in the mining of gold revealed in “The World’s 10 Most Prolific Gold Fields.”
1. Witwatersrand Basin (Johannesburg, South Africa)
The head frame of the Tau Tona Mine is the lone entrance to over 500 miles of tunnels.
Located in South Africa, the Witwatersrand Basin represents the richest gold field ever discovered. It is estimated the 40% of all of the gold ever mined has come out of the Basin. In 1970, South Africa’s output accounted for 79% of the world’s gold production. By 2009, South Africa’s share of world gold production had dropped to less than 8%.
Mining in the Witwatersrand Basin is accomplished by creating deep underground tunnels that are necessary to reach the plentiful reserves. The Tau Tona Mine features the deepest tunnel in the world extending a full 2.4 miles below the earth’s surface. A massive ventilation and air conditioning system is required to overcome the extreme working conditions throughout the over 500 miles of tunnels. At its deepest levels, the air temperature reaches 131 F and the rock face itself 140 F. The mine is so extensive that it takes workers a full two hours to travel from the surface to the deepest sections of the mine where they must then contend with pockets of lethal gas, water and a continual barrage of small earthquakes.
The discovery of gold in the Basin in 1886 by Australian miner George Walker set off one of the largest gold rushes in history. The surrounding area became the city of Johannesburg, and within ten years Johannesburg was the largest city in South Africa. The huge influx of foreigners (mostly British) created resentment among the Boer (prior Dutch settlers). Imposition of heavy taxes and restriction of voting rights by the Boer led to the Second Boer War in 1899.
National Geographic documentary Megastructures: Tau Tona City of Gold.
2. Carlin Trend (Nevada, US)
A large open pit excavation at the Twin Creeks Mine in the Carlin Trend.
For over a hundred years, prospectors in the Western US completely missed one of the richest gold fields in the world as it contained what is now popularly called ‘invisible gold.’ Historically, most gold fields were discovered by the presence of gold veins or deposits visible to the naked eye. Not so in the Carlin Trend located in northeast Nevada. Hot springs containing dissolved gold deposited the metal into the sediment in such fine particles that it is difficult to see even with a microscope and impossible to find using older conventional methods such as hand tools and panning.
In 1961, John Livermore, a geologist for Newmont Mining, set out in search of this invisible gold based on some ideas in a paper published a year before by noted geologist Ralph Roberts. It didn’t take long before Livermore found what he was looking for in an area that is now known as the Carlin Trend. The deposit was the first major one of its kind discovered. Subsequent discoveries of similar type areas in China and Macedonia are referred to as Carlin Trend type deposits.
Mining by Newmont began in 1965; the area has since become one of the richest gold fields in the world. Open pit mining dominates the Carlin Trend over its five by 40 mile area although some underground operations have been formed in higher grade areas.
Gold production in the state of Nevada, which is dominated by the Carlin Trend, accounts for almost 80% of the gold mined in the United States. If Nevada were a country, it would rank #4 in the world in terms of total gold production.
3. Irian Jaya (Indonesia)
The Grasberg Mine’s opening is 1 mile in diameter.
In one of the most inaccessible spots on the planet lie the single largest gold ore body and third largest copper ore body ever discovered. Located in the mountains of Irian Jaya, Indonesia, at an elevation of 14,010 ft, is the Grasberg Mine. Two miles away lies its predecessor, the Ertsberg Mine. The amazing feat of their construction by Freeport McMoRan is the subject of an episode of Discovery Channel’s Super Structures.
Work on the original Ertsberg Mine began in 1967 with the construction of a dock and a 25 mile road through the surrounding jungle. Chain saw wielding workers were lowered from helicopters to cut their way clear to the jungle floor. Bulldozers were flown in where they often had to contend with 20 feet of soft marshland before reach solid ground. The final section of mountain road was built atop a ridge so narrow that the first clearing pass had to be done with bulldozers no bigger than riding lawn mowers. Six subsequent iterations of air lifting increasingly larger bulldozers were used to complete the road. A tram system had to be built to surmount the final 2,000 foot cliff that separates the road from the mine site.
Getting the mined ore off of the mountain is a much more efficient process: it is simply dropped 2,000 feet to the giant crushers below. The processed ore is mixed with water to create a gold and copper slurry which travels through 70 miles of pipe out to the shore. From there, the slurry is concentrated and the ore then transported to smelters around the world.
The original Ertsberg Mine operated from 1972 until it was depleted in the mid 1980s. In 1988, Freeport McMoRan discovered the enormous neighboring ore body that is today operating as the Grasberg Mine. Gold production was 2.5 million ounces in 2009. Open pit operations will continue through 2015 at which point the gold will be mined by underground methods.
Grasberg: Gold Mine in the Sky. Super Structures. Discovery Channel
For the rest of this article, please go to: http://www.cmi-gold-silver.com/blog/10-most-prolific-gold-fields-in-the-world/