Despite their name, rare earth elements are relatively plentiful in the Earth's crust (with the exception of the highly unstable promethium). However, because of their geochemical properties, rare earth elements are not often found in concentrated exploitable ore deposits. It was the very scarcity of these minerals that led to the term "rare earth".
High-technology and environmental applications of the rare earth elements (REE) have grown dramatically in diversity and importance. Technological products range from computer components such as flat panel displays and hard drives to fibre optics and health care technologies such as magnetic resonance imaging (MRI). New environmentally green technologies also use REE's in everything from energy efficient compact fluorescent light bulbs to hybrid cars, catalytic converters to zero emmission wind turbine generators. Many strategic defense applications are also reliant on REE's, such as missile guidance systems, anti-missile defense and communication systems. A great deal of these applications are highly specific and substitutes for the REE are either inferior or unknown, thus REE's have gained a level of technological and economic significance in recent years. Most of the world's supply comes from only a few sources.
The strategic value of secure Rare Earth supplies was understood in China much earlier than in the western world. Under the late leader, Deng Xiaoping, China embarked on a course to become the world's preeminent supplier of these elements and now it accounts for 95% of the world's production. The United States once was largely self-sufficient in REE's, but in the past decade has become, along with many other advanced economies, reliant on imports from China. In recent years, China has implemented production quotas, enforced environmental regulations on REE producers and introduced export quotas and restrictions. As a result of the increased demand and tightening restrictions on exports of the metals from China, searches for alternative REE sources are now ongoing.