Chinese suppliers are rationing rare earths, critical to electronic modules.

FORBES: Selling More for Less or Selling Less for More?

This week's ruling applies to materials like bauxite, coke, magnesium, manganese and zinc, but, most notably, does not apply to rare earths -- a group of 17 elements critical to the production of tablets, smartphones and myriad other gadgets.

ENGADGET: WTO ruling revives debate over China's rare earths trade

The EU sees "especially strong potential" in Greenland's deposits of niobium, platinum, rare earths and tantalum, among the elements on an EU "critical raw materials" list.

BBC: Greenland rare earths: No special favours for EU