470 



UNITED STATES MINERAL RESOURCES 



Figure 56. — United States, South African, and world production of monazite, 1887-1970. Data for 1887-1947 from Olson 

 and Overstreet (1964, fig. 1) ; 1948-70, from U.S. Bureau of Mines (1950-72). 



United States from 1947 through 1968 for 

 nonenergy uses. 

 Near Elliot Lake, Canada, thorium was first re- 

 covered from Precambrian uranium-bearing 

 conglomerates in 1959, from ore containing 

 about 0.05 percent ThOj (Williams, 1969, p. 

 487). The thorium was recovered from effluent 

 solutions by ion exchange following the re- 

 moval of the uranium, and was precipitated as 

 a concentrate that contained 25-40 percent 

 ThOz. The ThOz was recovered from only a 



small part of the uranium ore mined. Thorium 

 shipments in Canada in the period 1966-69 

 contained a total of about 186 tons of ThOz, 

 only a small part of the capacities of the mills, 

 but lack of market caused production to cease 

 in 1968. Most of the concentrates were shipped 

 to Thorium Ltd. in Great Britain, although 

 some was shipped to the United States and 

 some was used in Canada for making thorium 

 metal. 

 In 1957, 132 tons of thorium-bearing ores was re- 



