What OPEC is to oil, China is to rare earth elements, and the Chinese government is now taking advantage of its control over such materials to expand its economic clout. China possesses 93% of the world’s rare elements, and virtually all of the global supply of dysprosium and terbium. These and other rare elements are essential for the production of green energy technologies, such as wind turbines and the batteries for hybrid cars, not to mention iPods, air bag sensors, MRI machines and military weapons like missiles.