"Until 1948, most of the world's rare earths were sourced from placer sand deposits in India and Brazil. Through the 1950s, South Africa took the status as the world's rare earth source, after large veins of rare earth bearing monazite were discovered there. Through the 1960s until the 1980s, the Mountain Pass rare earth mine in California was the leading producer. Today, the Indian and South African deposits still produce some rare earth concentrates, but they are dwarfed by the scale of Chinese production. China now produces over 97% of the world's rare earth supply, mostly in Inner Mongolia, even though it has only 37% of proven reserves. All of the world's heavy rare earths (such as dysprosium) come from Chinese rare earth sources such as the polymetallic Bayan Obo deposit.
New demand has recently strained supply, and there is growing concern that the world may soon face a shortage of the rare earths. In several years, worldwide demand for rare earth elements is expected to exceed supply by 40,000 tonnes annually unless major new sources are developed.
These concerns have intensified due to the actions of China, the predominate supplier. Specifically, China has announced regulations on exports and a crackdown on smuggling. On September 1, 2009, China announced plans to reduce its export quota to 35,000 tons per year in 2010-2015, ostensibly to conserve scarce resources and protect the environment. On October 19, 2010 China Daily, citing an unnamed Ministry of Commerce official, reported that China will "further reduce quotas for rare earth exports by 30 percent at most next year to protect the precious metals from over-exploitation".
As a result of the increased demand and tightening restrictions on exports of the metals from China, searches for alternative sources in Australia, Brazil, Canada, South Africa, and the United States are ongoing. Mines in these countries were closed when China undercut world prices in the 1990s, and it will take a few years to restart production as there are many barriers to entry. One example is the Mountain Pass mine in California, which is projected to reopen in 2011. Other significant sites under development outside of China include the Nolans Project in Central Australia, the remote Hoidas Lake project in northern Canada, and the Mount Weld project in Australia. The Hoidas Lake project has the potential to supply about 10% of the $1 billion of REE consumption that occurs in North America every year. Vietnam signed an agreement in October 2010 to supply Japan with rare earths from its northwestern Lai Châu Province.
Also under consideration for mining are a sites such at Thor Lake in the Northwest Territories, various locations in Vietnam, and a site in Southeast Nebraska, where Quantum Rare Earth Development, a Canadian company, is currently conducting test drilling and economic feasibility studies toward opening a niobium mine. Additionally, a large deposit of rare earth minerals was recently discovered in Kvanefjeld in southern Greenland. Pre-feasibility drilling at this site has confirmed significant quantities of black lujavrite, which contains about 1% rare earth oxides (REO). 
Another recently developed source of rare earths is electronic waste and other wastes that have significant rare earth components. New advances in recycling technology have made extraction of rare earths from these materials more feasible, and recycling plants are currently operating in Japan, where there is an estimated 300,000 tons of rare earths stored in unused electronics."