Bolivia's exhausted Cerro Rico mountain risks collapse
At the foothill of the Cerro Rico, the market on Plaza El Calvario is every miner's first stop before entering the "rich mountain".
The sun has yet to rise over the eastern peaks that surround the Bolivian city of Potosi, and young men huddle inside food stalls slurping steamy soups for breakfast.
Along the main route to the Cerro, other shops sell dynamite, cigarettes and coca leaves, catering to the 15,000 men, women and children who work in the mines.
"I chew it so I can work underground," says Trifon, as he buys a small bag of coca. "It gives me strength and energy, and it helps me to not feel hungry."
The young miner will spend the next 12 hours in a maze of hundreds of tunnels.
Looming over the city, the mountain has been exploited ever since silver was first discovered in 1545, but after almost five centuries it is showing warning signs of exhaustion.
Its peak has lost its once perfect cone-like shape. In January a huge crater formed at the top, and geologists are worried that the mountain may be at risk of collapse.
Hilarion Andrade of Comibol, the government's mining authority, said the crater - which measures 350 sq m (3767 sq feet) in area and 20m (65ft) in depth - proved the fragility of the mountain. He blamed the crater's formation on the uninterrupted exploitation of the past.
"Tunnels that were dug were left empty and this caused an imbalance," he said. "That's why the ground sank."
The city's ombudsman, Rene Arroyo, wants action to preserve the cone-like shape of the mountain.
"The Cerro is telling us something. It's telling us: 'I'm sinking.' And it wants our support," he said.
"We are worried that the Cerro could collapse on its own and kill many of the workers."
But heeding calls to stop mining in the Cerro Rico could be devastating for Potosi.
Almost half of the city's 200,000 residents work for the mining sector in some way, benefiting from minerals like tin, zinc and copper.
Mr Arroyo thinks the authorities should first reduce the city's dependency on mining.
"But unfortunately there hasn't been the political will to find other work for the miners," he said.
The governor of Potosi, Felix Gonzalez, has set up a commission to investigate possible new dangers at Cerro Rico and to find sustainable alternatives for its workers.
"I believe there are technologies nowadays that allow us to preserve the Cerro Rico," he said.
"We are also looking into the possibility of mining in other mountains so that people can have alternatives for employment."
For Julio Quinones, who represents the dozens of mining cooperatives in the Cerro, there is no reason to be alarmed.
"We are there every day, and we believe that the Cerro will not suffer any of the damage claimed by the government," he said.
Mr Quinones admits that mining still goes on in some of the most dangerous areas, which puts lives at risk. But he feels it is justified, because miners need to feed their families.
The mines of Cerro Rico were a source of riches for Spain from the 16th Century until the end of colonial rule nearly 300 years later. Tonnes of silver were mined and sent to the Spanish crown.
The mines are much emptier today and the dwindling population is one of the poorest in Bolivia.
No other options
Inside one of the oldest mines, hissing pipelines run along the walls, carrying compressed air for the operation of drills.
Wearing rubber boots, miners work in dark tunnels with small lights mounted on their hard hats.
Conditions have changed little since the Spanish ran the mines. Deadly accidents are common, and most miners still die young with lung disease caused by years of inhaling poisonous dust and gases.
Nestor Condori, who is 29, says he has no option but to work as a miner.
"Nobody likes doing this job, but it's the only one in Potosi," he says.
He has been doing it since he was 15, and worries about what would happen if new mining restrictions were imposed.
"I would have to find other work… or go to the United States," he said.
His sentiments are shared by Omar Garcia, another young miner.
"In the city you can only get a job in the mining sector," he says. "So I'd have to move to find other work. I have no choice."
The authorities in Potosi are not suggesting halting mining altogether in the Cerro Rico.
But like silver, one day, all its riches will run out. Potosi does not seem ready for this looming prospect.