It is the oldest gold mine in Colombia. For over 500 years locals have tunnelled deep into the mountains of Marmato, in the department of Caldas, risking their lives for the sake of the precious metal. Upon crossing the region in 1536, Spanish conqueror Sebastián de Belalcázar was astonished by the rich gold pieces worn by the indigenous people who dwelled in the area. Since that first contact with the Old World, Marmato’s gold fuelled many domestic and international enterprises, before it gradually came back to local ownership. Today, the town is home to 9.000 inhabitants. Their only “sin” (as they like to put it), is to be sitting on one of the world’s last great known reserves of gold: billions of dollars worth of it.

After decades of small-scale mining, their sin has recently earned them a new curse. In 2006, as the Colombian government opened its doors to foreign investment in the mining sector, Cana- dian capital started pouring into Marmato through a company called Medoro Resources. In less than a year, Medoro bought over 80 percent of the mines of Marmato, pursuing the constitution of a single mining title in order to establish a huge open-pit mine that would level the gold-rich cerro El Burro, on which the centre of Marmato is located.

In 2008, American photographer Mark Grieco visited Marmato for the second time. He had discovered the town two years before after visiting the mines of Potosí, in Bolivia, and the harsh reality of mining towns fascinated him. Aware that a complex situation was brewing in Marmato, he settled in Medellín and started spending long periods of time in the town, sharing the miners’ daily life and getting to know Medoro’s technicians.

“One day he just showed up at the mine where I was working, asking if he could know more about our work”, recalls Marmato miner José Dumar Vélez. “He said he wanted to know our story. Over the years we became friends, he met my family and started filming us. It was a bit awkward at first, but then we all got used to his presence.”

While Mark multiplied his visits,  things got worse in Marmato. In 2010 the Colombian government, backing Medoro’s plan, restricted the supply of dynamite in the municipality, officially to prevent terrorist activities in the area. Without this essential tool, the miners had to stop working and hundreds lost their jobs. Medoro, who had then changed its name to Gran Colombia Gold, was stepping in strong.

“They chose to resist with what they do best: keep working”, explains Grieco. Using homemade dynamite, the miners were back in the tunnels, and with the blasts came more trouble. In 2011, claiming ownership of the mines, Gran Colombia Gold started closing them up behind heavy iron gates, blocking the entrance to the tunnels and ignoring its promises of employment and decent income for the miners. There was no doubt: Gran Colombia Gold simply wanted them out of Marmato.

Caught between unemployment and the perspective of displacement, the miners had no choice but to keep resisting. Forcing their way into the tunnels, they started working as “guaqueros”, illegal miners. In just a few years, they had become illicit on their own land.

Neither the failed talks with Gran Colombia Gold or the repeated attempts of the Colombian police to expel them at gunpoint made any difference. The miners of Marmato still refused to be kicked out. The Canadian firm, unable to implement its plan, gradually lost the confidence of its investors, and soon lacked the capital to buy the remaining mines. As time went by, the ownership of Mar- mato’s mines became disputed. The Marmateños now live in limbo. “Our future is very uncertain”, admits José Dumar. “We all feel deceived, trapped, and people are divided. Marmato has lost a lot of its values and culture in recent years.”

Through his camera, Mark Grieco was a patient witness of this decay for nearly six years. In 2013, he edited hundreds of hours of images into a neat, powerful and remarkably human 86-minute feature that premiered at the Sundance Film Festival last January. As they discovered the film last month during its Latin American premiere at the Cartagena International Film Festival, José Dumar and four of his fellow Marmateños were moved and proud. Their long-ignored story was finally told, and with it came a new tool for resistance.

Marmato’s fate resonates as the allegory of many Colombian towns, similarly affected by socially blind large-scale mining. Acknowledging the importance of Grieco’s work, the Festival considered it Best Colombian Film and Best Documentary. Winning the Audience Award, Marmato was the most prized film in Cartagena. And a story to keep a golden eye on when it reaches screens soon.