By Luisa Baldini
BBC News, Chile
Local farmers fear water contamination from the mine
High in the Andes, on the border of Chile and Argentina, lies a mountain of hidden gold.
It is called Pascua Lama and contains so much of the precious metal it will take 20 years to extract.
That is exactly what Canada's Barrick Gold Corporation plans to do after being given the go-ahead by both Chile and Argentina.
Already Pascua Lama is criss-crossed with roads built by the company when it was carrying out exploratory missions, and within a few years the mountain will be stripped bare as the digging begins.
Tons of gold-bearing ore need to be excavated to produce a single ounce of bullion. Once the rock has been pulverised, cyanide is used in a leaching process to extract gold and silver.
The waters that flow from the area's three glaciers are crucial to local communities because the water supplies the Huasco Valley and lowlands enabling crops to grow in the desert landscape.
But some farmers fear the mine will contaminate the water ruining their livelihoods.
One of them is Mario Mautz who grows avocados, which would be impossible if it were not for the river which flows at the bottom of his farm.
He is sceptical about the promises Barrick has made to monitor the water.
"Barrick are attacking our rivers, our glaciers, our ancestral water rights. And that is why I think I should go on fighting them," he says.
"We are going to write to the United Nations and international courts. We want to tell them point by point that this project is not good for the environment. And we hope that they will intervene."
Mr Mautz's views are shared by many environmentalists including Sara Larrain from Sustainable Chile.
I really think that Pascua Lama is sustainable
Maria de la Luz Velasquez
Chilean Mining Ministry spokeswoman
She fears movement and dust from the drilling will destroy the glaciers.
Opposition to the project is clear to see. As you drive through the Huasco Valley there are several improvised signs - graffiti reading "Barrick out" and "Save our water".
Not only are there fears that the environment will be destroyed, but also that there will be seismic changes in the culture of the valley where the indigenous Diaguita people have lived for centuries.
But some local residents like cafe owner Elena Belis support the mine because it will provide better-paid jobs.
That is also one of the reasons why the Chilean government backs the scheme.
Pascua Lama is expected to begin to yield gold in 2009
Mining Ministry spokeswoman Maria de la Luz Velasquez acknowledges that a project like Pascua Lama will bring changes.
But she says: "If we don't do it, what's the alternative? There are jobs in agriculture but often only seasonal. I really think that Pascua Lama is sustainable."
Chile will receive taxes and royalties but insists there will be vigorous controls on the project.
For their part Barrick say their modern mining methods are fail-safe and that they have taken measures to safeguard the environment.
For example, they have 34 water monitoring stations in the area to check the quality of the water, 30 of which will transmit data in real time to environmental authorities and the public.
Molten gold from Pascua Lama will begin to flow in 2009 and it seems activists have little hope of stopping it.
While the area will benefit from investment, when the mine is exhausted and Barrick have gone, what will the legacy of Pascua Lama be?