Rare-earth metals are critical to the production of a number of high-tech products, including permanent-magnet generators (PMG) for wind turbines, of which Finland's The Switch is a leading supplier.

The price of rare-earths surged in early 2011 on fears that China had begun clamping down on their export in order to protect its own high-tech industries.

The spike prodded new non-Chinese producers into the sector, such as Molycorp, and led some in the wind business to question the future of permanent-magnet direct-drive turbines.

But