every day, robi vaden digs deeper into the ground in search of tin, one of the most sought-after of precious metals, now that it's used in every mobile phone. >> you might say we risk our lives so others can use their telephones. it happens all the time: the hill caves in on you, and you're buried alive. prospecting for tin is fairly dangerous. >> bangka off the coast of sumatra is a treasure island. buried in its soil is more tin per cubic meter than anywhere else on earth. tin has made the island rich, and brutally destroyed it. bangka has become a vast no-man's land, it's landscape a sea of craters. most of the tin mining is illegal. the island is riddled with thousands of improvised mines. the earth is sucked up through big hoses and washed until nothing remains but the precious black metal. whole families live from mining: housewives, young men, the elderly, teenagers... even children. cynthia is just twelve. >> i come here all the time after school. working in the mine is fun. >> the big manufacturers of mobile phones, tablets and other devices make no secret of the fact that they draw