The United States continues to be the world's leading producer and consumer of diatomite. Production of diatomite in the United States during 2011 was estimated to be 600 kt (661,000 st), a slight increase compared with 2010 production. The unit value of diatomite varied widely by end use in 2011. Diatomite used as a lightweight aggregate was priced at $8.82/t ($8/st), while specialty-grade diatomite, used in art supplies, cosmetics, or biomedical applications, was priced as high as $10,000/t ($9,070/st) on a spot basis. Filter-grade diatomite had an average unit value of $394/t ($357/st). Seven companies operated 10 mines an nine processing facilities in California, Nevada, Oregon and Washington. U.S. diatomite exports totaled about 120 kt (132,000 st). Imports were much lower, at approximately 1 kt (1,100 st).