Mining is no friend of the planet: erosion, deforestation, groundwater contamination, silting, the list goes on. Here's a more direct look at another of its impacts: the human cost.

The Devil's Miner, a documentary by Richard Ladkani and Kief Davidson observes the thousands of miners, hundreds of them children, scouring the silver mines at Cerro Rico, the "rich mountain" outside Potosi, Bolivia.

Mined since 16th century, the Cerro Rico - said to have produced enough silver to build a bridge from South America to Spain - has an ugly history of forced Indian labor, mercury poisoning and, more recently, severe economic decline, as the bulk of its silver riches is long gone. Modern-day miners are referred to as the "scavengers of Cerro Rico."

The Devil's Miner follows the narrator, 14-year-old Basilio Vargas, and his brother Bernardino, 12, as they work the mines to support themselves and their single mother and pay for their own schooling. As they contend with toxic gases and collapsing tunnels, miners chew coca leaves for courage and calm, and pray to the devil to protect them in his subterranean domain; they call the devil Tio ("Uncle") and build altars to him throughout the mines.

The documentary premiered at last year's Tribeca Film Festival, so we're a little late to the show, but one of our favorite deep-think blogs, WorldChanging, just posted its review.

According to WorldChanging, the film has become an incredible advocacy tool in the year since its release, with aid organizations CARE and Kindernothilfe working to improve children's lives in Potosi, and the film has been shown to an American company planning to open a Cerro Rico mine. A percentage of DVD sales will go to Kindernothilfe; the film's website has more ways to help.

Photo credit: http://www.thedevilsminer.com/