An underground gold war in Colombia is 'a ticking ecological time ...

Nearly 100 underground tunnels, running a combined length of more than 84 kilometers, or 52 miles, crisscross and plunge into the depths of the mountain that hosts the Zijin gold mine in Buriticá, northeastern Colombia. Since 2021, those tunnels have been invaded by informal miners associated with Colombia’s largest criminal armed group, the Gaitanista Army of Colombia (EGC), called the “Gulf Clan” by the government, who are digging their own honeycomb of tunnels into the same massive gold deposits.

Confrontations between the informal miners Zijin security personnel have at times escalated into underground gun battles. And as the mine acts as a magnet for increasing criminality, both social and environmental destruction have followed.

Residents describe the situation as “a ticking ecological time bomb.” Some say they worry that the thousands of poorly constructed tunnels built by the informal miners are in danger of collapsing the mountain entirely — a fear also expressed after investigations by the Mining, Environmental and Agrarian Office of Colombia’s Attorney General’s Office.

Concerns over contamination

In a public statement from July, the AGO warned that illegal mining is creating “grave environmental consequences” that include “structural geological risk to the base” of the mountain where the Zijin mine is located.

“All mining, legal or illegal, contributes to ecological damage, and potentially threatens water tables via underground aquifers, causes deforestation and in turn these phenomena threaten biodiversity,” Oscar Alejandro Pérez-Escobar, a Colombian researcher at the Royal Botanic Gardens, Kew, in the U.K., told Mongabay. “The region where Buriticá is located is among the most biodiverse in the Andes.”

But illegal mining is often more damaging than licensed commercial mining operations, because the miners don’t follow state-imposed practices that include basic ecological and safety guidelines, he said.

Many of the informal mining operations that have sprung up around the mine use mercury as an agent to extract the gold deposits from the ore, as well as explosives to create tunnels or erode mountain faces, and heavy machinery to clear forest for strip-mining.

These illegal underground operations also damage the water table in the region through the use of chemicals and by leaving mining waste, or tailings, in poorly constructed tunnels that stretch deep into the mountain range in which they’re constructed.

“This is incredibly concerning,” Pérez-Escobar said, noting that any toxic materials left in the tunnels “will immediately end up in the water table. The tunnels are dug directly through natural subterranean aquifers in the mountains.”

“Heavy metals left over from mining, or used in mining processes, such as mercury, make their way up through the water table, into the food chain, and threaten flora and fauna alike,” he said. “This eventually becomes a poison for every living thing in the region.”

Mercury, which causes neurological damage in humans, including developmental problems in infants, has been detected in residents of other regions of Colombia where illegal mining has long been prevalent.

A 2017 study by the country’s environmental ministry in the municipalities of Segovia and Remedios found “high levels of mercury” in the breast milk of nearly 12% of lactating mothers. The government of Antioquia department, where the two municipalities are located, didn’t immediately respond to questions sent by Mongabay about whether similar studies had been conducted or were planned in Buriticá.

The Zijin mine operator has also been accused by the informal miners of intentionally dumping “toxic sludge” in tunnels in an attempt to deter illegal miners from entering. The operator has denied the accusations.

A growing minefield

The Zijin mine sits on the largest known gold deposit in South America,  an estimated reserve of more than 300 metric tons. The Chinese mining conglomerate that operates it calls it “ultra high-grade” and the country’s “first modern underground mine.”

But amid growing tensions with some local community members since the mine opened in 2020, the Chinese company has been the target of protests and road blockades by informal miners in the region.

The mine was initially built following surveying by Canada-based Continental Gold between 2016 and 2019, which discovered the gold deposits in Buriticá. In 2019, Zijin Mining Group, a multinational Chinese conglomerate, acquired 69.28% of Continental Gold’s shares and took over the Canadian company’s operations in Colombia.

Juan Guillermo Pineda is a firefighter who has lived his whole life in Buriticá. “The illegal miners dump the bodies of those who die in the Zijin tunnels,” he told Mongabay over coffee in the idyllic town square. “They know they’ll be found there. So we come to pick them up, identify them, and then notify the families. If there are any families.”

Pineda adds that “We used to all be farmers here. But the kids here aren’t interested in that. Why would they want to poke around in the dirt when they earn 20 times as much looking for gold?”

Previously, the Gaitanistas didn’t have much of a presence in the municipality, despite having effective control over the region. But after Continental Gold’s discovery, things quickly began to change.

“A lot of people started arriving here from other mining regions in the country [in 2020],” said an activist and social leader who asked for anonymity, citing safety concerns. “People started to come here from dangerous places, like Segovia,” a mining town in northern Antioquia where the Gulf Clan maintains a strong presence. The region has a murder rate eight times higher than the national average.

“And now everyone has to pay EGC,” the activist said. “But the extortion isn’t the worst of it. Informal mining has exploded, and deaths have come with that.”

Zijin invested heavily in infrastructure and mining titles in the region. After operations became increasingly dangerous, in 2024 the company filed a lawsuit against the Colombian government. It sought $500 million in damages under Colombian-Canadian trade agreements, claiming Colombia had failed to guarantee basic security for its investment.

In June 2024, Zijin publicly declared it had lost control of more than 60% of its mining operation, as tunnels had been taken over or collapsed by informal miners, while two employees had been killed and dozens more injured. In the same statement, the company announced that it had recorded “2,260 explosions using improvised artifacts” and “a total of 2,450 shots fired” during confrontations with illegal miners within its tunnels in 2023.

“The Canadians dressed up the mine, claimed it was safe, and walked away with a nice paycheck,” said Luis, a mid-level manager for Zijin’s operations in Buriticá. He asked that his last name be withheld because he doesn’t have authorization to speak on behalf of the company. “It isn’t the Chinese company’s fault the problems started right afterward.”

But Zijin’s lawsuit against Colombia is “unlikely to succeed,” said Adriaan Alsema, executive editor of South America-focused news portal Colombia Reports, who has reported on similar legal battles in the past. “The fact that Buriticá rests in a region firmly controlled by EGC is public knowledge. Government lawyers are likely to argue that it was a lack of due diligence on the part of the international conglomerate that is to blame, not Colombian security forces”

Alsema added that “No one is forcing the Zijin mining group to conduct operations here.”

Since 2020, when the Zijin mine opened, Colombian authorities have deployed 50 police from the National Unit Against Illegal Mining and Terrorism (UNMIL), who provide 24-hour security inside the mine, and hundreds of uniformed officers in the regions around Buriticá, where the illegal tunnel entrances are located.

“It hasn’t been enough,” said the activist. They added, however, that many of the informal miners being blamed for environmental and social problems are victims of the organized crime dynamic as well.

Most informal miners there are young and come to Buriticá from all over the country, searching for what seems to be a surefire way to make money.

“These kids are locked underground for weeks. They have no cellphone service, no entertainment,” the activist said. “So a lot of them turn to cocaine or other drugs to aid with the tedium of the work.”

They work shifts of 20 to 30 days locked in the tunnels. Although they can order food and even drugs from those who manage the illegal mining operation, they must pay out of their earnings.

“Some of them, if they’re unlucky, end up in debt,” the activist said.

But more often, miners who are paid based on the amount of ore they extract by the “investors” who oversee the illegal mines, can earn five to six times the monthly minimum wage in Colombia  —  currently around $360.

“Sometimes, if they strike a rich vein, they can make more though,” Pineda said. He described the work as incredibly dangerous, with workers drowning in floods in badly constructed tunnels, asphyxiated from a lack of proper ventilation, crushed by tunnel collapses that are either unprovoked or triggered by explosives used in mining operations.

“If someone is working in an adjacent illegal tunnel when Zijin workers are using explosives, it can burn all the oxygen in the air for hundreds of meters,” Pineda told Mongabay. “Informal miners have died not even realizing they are suffocating.”

For Luis, the Zijin mine manager, the solution is “a purge.” “Security forces need to clear out all of these strangers who come here and commit crimes. If Zijin leaves, the mine will just become even more of a magnet for armed groups,” he said.

But the activist said the solution isn’t that simple. “You can’t put these kids in jail for accepting an opportunity to improve their economic situation that they view as legitimate,” they said. “They are victims of the armed conflict as much as anyone else. And Zijin, despite their claims otherwise, knew the situation they were getting into.

“They just thought the profit would exceed the risk,” they added.

The departmental government and the Attorney General’s Office have launched programs in cooperation with Zijin to formalize illegal miners in the region, who must undergo environmental and safety training to be granted licenses.

Hugo Valle works as a subcontractor in the program to help the illegal miners enroll. “Mining has to be done in a responsible and sustainable manner,” he told Mongabay. “[President Gustavo] Petro has made environmentalism one of the primary goals of his administration, but we see no presence from the national government.

“Tons of illegal explosives and mercury are entering our town,” he added. “And this industry, carried out by thousands of [illegal] miners, also increases deforestation. They need wood to build their operations. We have already identified two species of trees near extinction that exist only in this region.”

Pérez-Escobar, the ecologist, spoke of a “strong link in Colombia between conflict and environmental destruction. Many times it is the human cost that is more visible,” he said.

“But environmental damage is often less immediately visible and may take decades to repair.”

Banner image: Buriticá is among the most diverse regions in the Andes. Image by Joshua Collins.

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