Amazon Indians have for decades made a living exploring the rain forest for valuable rocks that contain metals such as tantalum and tungsten, which are used in products manufactured by some of the world's best-known companies. Tungsten, in particular, is in high demand, Bloomberg Markets reports in its September 2013 issue. The dark, heat-resistant and superhard metal is exported to the U.S., where it's processed and later sold to companies that make cars, televisions, smartphones, tablets, computers, ball-point pens and more. Here, on the Inirida River in Colombia's Amazon, a work crew from the illegal Tiger Hill tungsten mine drags a boat past rapids. Workers have to brave half a dozen sets of deadly rapids to get to the mine from the nearest town.
Click here to read more about tungsten’s tainted trail in the September 2013 issue of Bloomberg Markets.