INFOGRAPHIC: Metals and minerals used in renewable power generation

Depressed oil prices may end up helping, CEO Doug Oberhelman added.

The massive copper project, owned by Wanbao Mining Ltd, drew international attention in 2012 when police brutally dispersed protesters, injuring more than 100 Buddhist monks.

Steinmetz and three BSGR directors argued that Global Witness had obtained personal information about them without authorization and wanted it to be forced to reveal what specific data it held.

The touted expansion of the world's largest underground copper mine is two to three years behind schedule and will require $2 billion more than initially planned, said the company.

According to the legislators, international mining companies —mainly from Australia, Canada and the U.K— are using the forced labour of Eritreans in their operations.

The investigative reporting piece exposed extremely poor working conditions in factories making Apple products in China and Indonesia.

The German equipment manufacturer expects it to drop by at least 4.5% this year, about $317 million less than in 2013.

Unearthed at Alrosa's Udachnaya diamond mine, it was later donated for study as the diamonds it contained were pretty much worthless as gems.

China’s increased reliance on nuclear energy and Japan restarting its reactors are only two of the factors driving prices up.