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Rare earths: Colourful and magnetic

Although chemically almost indistinguishable, the rare earth elements possess unique electro-magnetic and optical properties that have made our modern electronic world possible.

But China dominates their supply, as the world discovered in 2010-11 when that supply was briefly choked off.

Presenter Justin Rowlatt gets the full rundown of these 15 elements' bizarre names - holmium, europium, promethium... - as well as the many surprising places they crop up in industry, from our favourite chemist, Andrea Sella of University College London.

He speaks to technology metals consultant Jack Lifton about what exactly did go on in 2010, causing the price of some rare earths to spike more than 20-fold.

Part of China's big competitive advantage has allegedly been a lack of regard for the environment, and Justin hears from the French journalist Cecile Bontron, who travelled all the way to China's remote rare earth mine at Bayan Obo in Inner Mongolia and the toxic processing plant at nearby Baotou.

He also travels to Denmark to visit Henrik Stiesdal of Siemens, discovering the critical role played by two of the rare earths in the wind turbine generators they manufacture, and how the firm has reacted to the 2010-11 Chinese supply scare.