A giant gold deposit could form in an eyeblink of geologic time, scientists announced today.
The large Ladolam deposit on Lihir Island in Papua New Guinea formed inside a recently extinct volcano and was ferried to the surface in solution by rising hot water.
By measuring the rate of gold that rises to the surface each year, the researchers estimate that the deposit could have formed in just 55,000 years. Our planet, by comparison, is about 4.5 billion years old.
“If the age of the Earth was scaled to a 24 hour day, the 55,000 years in which the Ladolam gold deposit formed is represented by the last second in that day,” said lead study author Stuart Simmons, a researcher from University of Auckland, New Zealand.
Gold is a dense and lustrous metal that has been valuable throughout human history. It is highly flexible, virtually indestructible, and extremely rare.
All of the gold ever mined can fit into a cube with 72-foot sides, Simmons told LiveScience.
The researchers lowered a custom-built titanium sampler, designed to collect hot water, into a half a mile deep well, where temperatures reached more than 480 degrees Fahrenheit.
This hot water comes from magma (molten rock) that intruded beneath the volcano, and it carries gold in solution. "When this hot water rises to the surface the gold precipitates forming the deposit,” Simmons said
With more than 1,100 tons of mineable gold, Ladolam is not only one of the youngest but one of the 10 largest gold mines that form in hydrothermal environments.
“It is unique in the world and nowhere else has there been a similar discovery,” Simmons said. “Moreover, the mining is a testament to engineering efforts to safely extract mineral resources from the Earth. The hydrothermal solutions which have to be removed from the mine site are simultaneously used to generate electricity from a renewable resource.”
The study is detailed in the Oct. 13 issue of the journal Science.
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