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A general view of activity along the banks of Ikopa river in Madagascar's capital Antananarivo, December 22, 2013, where washerwomen wash laundry for about 2,000 Ar (less than $1) a day. The Indian Ocean island has faced uncertainty for years, and is struggling to regain the confidence of foreign investors who had been eyeing deposits of oil, gold, chrome and uranium but were deterred by the coup and subsequent instability. REUTERS/Thomas Mukoya

A new study suggests that the source of the largest deposit of gold in the world could be a combination of agents. A scientist was of the belief that volcanic activity, coupled with ancient microbes, as well as oxygen-depleted atmosphere could be the source for the largest trove of gold. The study was published on Feb 1 in Nature Geoscience, a journal which publishes articles about Earth Sciences.

Christoph Heinrich is the study author as well as a geologist at ETH Zurich, Switzerland. He said that this could be the reason that a number of gold deposits were seen at the Witwatersrand basin in South Africa. He also said that the gold beds in South Africa could account to 40 percent of gold that has been dug out.

Initially, scientists were of the belief that gold was deposited in the streambeds of mountains like in the case of the Sierra Nevada mountains in California. Since the Witwatersrand basin is nowhere close to a mountain, this theory could not be accepted in this case.

Heinrich went on to say that this gold deposit is three times bigger when compared to the next biggest gold deposit. The second-biggest single gold deposit is the Muruntau gold deposit located in a desert in Uzbekistan. He said that gold had been part of the Earth for about 4.6 billion years and that most of it is locked within the core of the planet. He added that the rest of the gold was dispersed through rocks.

While taking into consideration the deposit of gold at Witwatersrand, Heinrich said that up to 1 percent of the carbon-rich layers of the basin was made of gold. He explained that a physical phenomenon resulted in the gold becoming a part of the layers of the rock.

Heinrich suggested a few circumstances that could have resulted in the formation of the gold deposit between 2.9 billion to 2.7 billion years ago. He said that the flow of the lava emitted sulfurous gas and the sulfur formed acid rain, which ate up the rocks containing the gold. This resulted in the rocks as well as the gold entering waterways. The sulfur combined wih hydrogen to become hydrogen sulfide which also entered the waterways and changed the ability of the water to hold huge amounts of gold.

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