A New York Times reporter followed a a force of Peruvian marines and rangers in a raid against illegal gold-miners in the Tambopata Nature Reserve, in the country's southern Amazon. Upon finding mining camps along the Río Malinowski, troops slashed bags of rice and plastic barrels of drinking water before setting everything on fire. But, massively outnumbered by perhaps 10,000 illegal miners in the area, they seem to be fighting a losing battle. They soon ran out of dynamite and resorted to a less sophisticated tactic: using mallets to smash the truck engines that miners use to power their derricks.

Deforestation from gold mining accelerated from 5,350 acres per year before 2008 to 15,180 acres per year after the 2008 financial crisis rocketed gold prices. In areas where the miners work, rangers say, the water is so polluted that the fish are all gone. Some advocates say Tambopata is all but lost. Early indications suggest that it is rich with gold, especially compared with other parts of remote Madre de Dios region—including the area officially reserved for artisanal mining and the "buffer zone" bordering the reserve.

"They are getting about 12 to 18 grams a day in the official mining corridor," said Victor Hugo Macedo, who oversees the reserve. "They are getting 60 to 80 grams in the buffer zone, and they are getting 150 to 200 in the reserve. The miners care more about that than what happens to Tambopata."

The miners use so much mercury to process the gold that the government declared a health emergency in much of the Madre de Dios region in May. Tests in 97 villages found that more than 40% of residents had absorbed dangerous levels of the heavy metal. Mercury poisoning affects people in many ways, from chronic headaches to kidney damage, but is most harmful to children, who may suffer permanent brain damage. "The next generations will pay for what we are doing now," said Peru's Environment Minister Manuel Pulgar-Vidal.