Uranium is the fuel for nuclear reactors. It is an actinide, and one of two actinides that are found in the earth's crust in more than trace amounts (the other being thorium).
Cameco (NYSE: CCJ) - http://www.cameco.com/operations/uranium/ - This Canadian company is the largest producer of uranium in the world. They operate the McArthur River mine, the largest high-grade uranium deposit in the world with proven/provable reserves of 389 million pounds U3O8 (triuranium octaoxide, or yellowcake). They also operate the Cigar Lake mine, home to the world's largest undeveloped high-grade uranium deposit, and the Key Lake and Rabbit Lake Mills, respectively the largest and second largest high-grade uranium milling operations in the world.
BHP Billiton (NYSE: BHP) - This large Australian diversified resources company also mines uranium. Australia is the second largest source of uranium, after Canada.
United States Enrichment Corporation (NYSE: USU) - USEC supplies low enriched uranium to commercial nuclear power plants. They supply uranium for about 150 nuclear reactors worldwide.
Nymex (NYSE: NMX) - The New York Mercantile Exchange offers a uranium futures contract for 250 pounds of yellowcake (U308).
Rio Tinto (NYSE: RTP) - http://www.riotinto.com/ Uranium One (TSE: UUU) - http://www.uranium1.com/
