Original Source: CNN

Six tourists wearing hard hats and heavy overalls sit, cramped up in a narrow mineshaft, with barely enough space to kneel. The local tour guide pulls out a disposable lighter, ignites a bright green fuse with it, and calmly ushers everyone backward. “Any moment,” he says.

A moment later, a powerful shockwave rips through the tunnel, tailed by a dust cloud.

He’s just set off a stick of dynamite bought at the local market earlier that day by one of the tourists — it cost 13 Bolivianos (just under $2). The Bolivian mining city of Potosí is the only place in the world where members of the public can legally buy dynamite.

“For the miners, the most essential thing is dynamite,” says Jhonny Condori, a Potosí mine tour guide. “If you don’t know how to handle it, it’s dangerous.”

But for experienced miners, it greatly speeds up the rate at which they can extract minerals.

Centuries old, Potosí’s network of mines is extensive. Miners run up and down long, narrow passageways, pushing carts full of fragmented rock along worn railway tracks — it’s a scene reminiscent of something from “Indiana Jones and the Temple of Doom” or Wario’s Gold Mine in Mario Kart.

Potosí is over 4,000 meters (13,000 feet) above sea level, making it one of the highest cities in the world. Its narrow streets and the red-tiled roofs and stucco walls of its buildings hint at its Spanish colonial past.

Much of the mining takes place within the adjacent, red-colored “Cerro Rico” (literally “Rich Mountain” in English) — so named because of the vast wealth it once brought to the city. Today, “Potosí is considered one of the poorest regions in all of Bolivia,” says Julio Vera Ayarachi, another local tour guide.

The Cerro Rico’s silver lining

Legend tells that the rich silver deposits of the Cerro Rico were first discovered by Diego Gualpa, an indigenous Andean prospector, who stumbled across them in 1545. “The secret got out. You can’t hide that kind of news,” says Kris Lane, professor of liberal arts at Tulane University in New Orleans, and author of “Potosí: The Silver City That Changed the World.”

Before long, Spanish colonizers — who had arrived in the region just a few years before — caught wind of the discovery and began exploiting the mountain’s abundant silver.

“It developed very quickly into a kind of nightmarish place,” says Lane. “It’s a place that’s lawless, it’s a place of forced labor.”

Indigenous people were obligated to work for and produce material tributes to the Spanish king, under a system that was “very close to enslavement,” he adds.

A surge of wealthy merchants began arriving from around the world to build infrastructure and profit from the mines. As techniques improved, conditions declined further, says Lane. Toxic mercury was introduced to the refining process, for example, which leached into the environment and led to the deaths of many. The Cerro Rico became known as “The Mountain That Eats Men” — a name that persists among miners to this day.

Potosí soon grew into to fourth largest city in the Christian world, with a population of more than 200,000 by the end of the 16th century. It’s thought to have supplied 60% of the world’s silver at the time, funding the Spanish empire and other dynasties around the globe.

“Silver crosses borders in a way that a bronze coin or a copper coin could not,” says Lane. Its relative scarcity gave it intrinsic value and “people came to expect that Potosí silver was trustworthy,” he says.

However, over time, the once seemingly endless silver reserves began to dry up. By the time Bolivia declared its independence in 1825, almost all the silver had already been mined and Potosí became a shell of its former self.

Though mining still goes on in there today, much of it is for cheaper minerals like tin and zinc. Hundreds of miles of mine shafts have made the mountain unstable — as a result, it is currently the “most dangerous time that the mines have witnessed,” says Lane.