Illegal exploitation, production and smuggling of rare earths in China have added to the supply glut, depressing global prices, according to China's vice-minister of industry, Su Bo.

China dominates the global market, producing over 90% of total rare earth metals.

In 2010 the Chinese government launched a campaign to curb illegal production ending operations for hundreds of unlicensed rare earth miners, processors and traders, and "leading to a fourfold spike in export prices and complaints from buyers in Europe, Japan and the United States."

Prices peaked in 2011 but have since fallen alongside sluggish global economic growth. Su says that their is much work to be done to diminish a black market that has traded roughly 40,000 tonnes of rare earths in recent years.