(Adds comments from Pope, resident)
By Mitra Taj
PUERTO MALDONADO, Peru, Jan 19 (Reuters) - Two decades ago, Swiss priest Xavier Arbex started sounding alarms.
The quiet Amazonian region where he had settled years earlier was in peril. Wildcat miners who once searched for gold alongside rivers using wheelbarrows and buckets had started tearing through pristine rainforest with heavy machinery.
"I knew this was going to be a big problem," Arbex said, describing his attempts to enlist heavyweight environmental groups to stop the looming disaster. "No one listened."
Wildcat gold mining in Madre de Dios has since flourished into a black market trade estimated to be worth billions of dollars a year, leaving gaping holes in the Amazon's forest cover and financing human trafficking and violent criminal networks.
Seeking to shine a light on the problem, Pope Francis visited the regional capital Puerto Maldonado, a steamy riverside town near Peru's border with Brazil and Bolivia. It was the pontiff's first stop outside the capital Lima on a three-day tour of Peru, which follows a trip to neighboring Chile.
While Francis has denounced environmental destruction before, he had yet to do so in a place as defined by it as Madre de Dios, where miners have dumped so much mercury into rivers that some fish are no longer considered safe to eat.
"Mining is the dynamite of the region's economy. Without it, we'd be poor again," said Juan Consa, 49. After toiling in mining camps in the 1990s, Consa was able to put his two kids through college and pay for the motorcycle taxi that now zips him around town.
"Even if you aren't a miner, in Puerto Maldonado you depend on it," said Consa, who opposed the pope's visit.
Francis issued a ringing defense of the people and the environment of the Amazon on Friday, lamenting the "sexual slavery" that takes place in mining camp brothels deep in the jungle. He later visited the home for abandoned youth that Arbex founded on the outskirts of town, thanking him for helping to mend the human toll of mining.
Francis urged the children sitting before him to follow "a way of life based on care and not destruction of everything standing in the path to our greed."
"I know there are wounds that hurt," Francis said. "Do not be resigned about what's happening."
Successive political leaders in Peru have failed to slow the illegal gold rush. President Pedro Pablo Kuczynski's plan to "formalize" miners who comply with labor and environmental laws has been derailed by political crises.
'HELL OF RICHES'
As mining has driven an economic boom in Madre de Dios, helping elect a former wildcat miner as governor of the region, it has also become increasingly violent.
Park rangers are regularly harassed by miners near the Tambopata nature reserve. Last year, authorities announced the discovery of a pit near mining camps where a criminal gang incinerated at least 20 victims. In September, a police officer was killed in an ambush during an environmental patrol.
"It's out of control," said Freddy Vracko, a third-generation Yugoslav-Peruvian tree farmer.
Vracko's father was shot dead by masked men in his home in December 2015 after his family endured years of death threats from encroaching miners. That prompted Vracko to run for governor in this year's regional elections.
"It's going to be a tipping point," Vracko said of the pope's visit to Puerto Maldonado. "No one has really wanted to solve this problem."
But for native communities, the illegal gold boom is only the latest sign of disdain that outsiders have shown for the Amazon, said Julio Cusurichi, head of a federation representing 36 indigenous communities in the region.
Once enslaved and massacred by ruthless rubber barons in the 19th century, native peoples are now being forced off ancestral lands by mining mafias. Many suffer from dangerous levels of mercury in their blood.
"Indigenous people drink water from rivers because we don't have running water in our homes. We eat fish from rivers because we don't buy meat from the market," said Cusurichi.
The miners themselves, often young men fleeing poverty in Andean villages, also suffer in makeshift mining pits.
"It's horrible," Arbex said, estimating that at least 250 miners die every year in mudslides or other unreported accidents. "They prefer a hell of riches to a poor paradise."
Environmental groups seized on the pope's visit to call for policies that encourage responsible small-scale mining while addressing the poverty that sustains it.
But Arbex said it might be too late to reverse the trend.
"I haven't lost faith in God but I have lost faith in policy," Arbex said.
(Reporting By Mitra Taj; Editing by Daniel Flynn, Frances Kerry and Tom Brown)
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