450 



UNITED STATES MINERAL RESOURCES 



ite, columbite, and monazite were the principal prod- 

 ucts, and ilmenite, magnetite, zircon, and garnet 

 were the stockpiled byproducts (Dayton, 1958). 



The euxenite placers of Bear Valley are thought 

 to be the result of a fortuitous combination of the 

 following factors: (1) Local concentrations of the 

 mineral in the quartz diorite and pegmatites, (2) 

 sufficient disintegration of the host rock to free the 

 minerals, (3) the action of Pleistocene glaciers 

 which dammed the local drainage and led to the 

 accumulation of valley fill, and (4) quickened down- 

 slope movement of enriched mantle during the peri- 



ods of glaciation (Mackin and Schmidt, 1956). 



Other placer deposits in Idaho, particularly the 

 Dismal Swamp deposit in Elmore County, contain 

 niobium and tantalum minerals (Armstrong, 1957 ; 

 Savage, 1961), but none of these are known to be 

 comparable in size or grade to those at Bear Valley. 



RESOURCES 



IDENTIFIED RESOURCES 



The most extensive resources of niobium and 

 tantalum (tables 89, 90, and 91) are found in Brazil, 

 Canada, and several African countries. Known re- 



Table 89. — Reserves of niobium and tantalum 



[Reserves: Identified deposits from which minerals can be extracted proiitably with existing technology and under present 



NbsOs content 

 (tons) 



TasOs content 

 (tons) 



North America 



Type of 

 deposit 



Canada : 



Lake Nippissing, Ontario 



Lakner Lake, Ontario 



Chapleau, Ontario 



James Bay, Ontario 



St. Honore, Quebec 



Oka, Quebec 



Bernic Lake, Manitoba 



Bugaboo Creek, British Columbia 

 Total 



5,000.000 



50,000,000 



20,000,000 



15,000,000 



40,000,000 



100,000,000 



225,000,000 



1,900,000 



(') 



United States: 



Iron Hill, Colo. 



Bear Valley, Idaho 



Harding mine, N. Hex. 

 Total 



40,000,000 

 100,000 



108,000 



4,370 



4,370 



2,000 

 100 



2,100 



Carbonatite. 

 Do. 

 Do. 



Do. 

 Do. 

 Do. 



Pegmatite. 

 Placer. 



Carbonatite. 



Placer. 



Pegmatite. 



South America 



Brazil : 



Araxa 



Tapira 



Tantalite deposits 

 Total 



300,000,000 

 10,000,000 



3.0 



.5 



Other: 



French Guiana (tantalite) 

 Guyana (tantalite) 



300,000 



9,000,000 

 50,000 



9,050,000 



500 



4,000 



4,000 



1,200 

 250 



Congo : 



Lueshe 



Bingo 



Columbite-tantalite 



Kenya: Mrima Hill __ 



30,000,000 

 7,100,000 



Nigeria : 



Kaffo Valley 

 Jos Plateau - 

 Uganda : Sukulu 

 Malawi: Ilomba - 

 Total 



56,000,000 

 50,000,000 



140,000,000 



1.34 

 2.4-3.6 



.67 



.7 



200,000,000 

 100,000 



.26 



.25 

 .33 



402,000 



198,000 



50,000 



375,200 

 350,000 



364,000 



100,000 



500,000 



300 



2,744,500 



50,000 



yd. 



= 200,000,000 cu yd. 



' Estimated euxenite content, 1 lb per ( 



60,000 



yd. 



Carbonatite. 



Do. 

 Pegmatite. 



Do. 

 Do. 



Do. 

 Do. 



Pegmatite- 

 placer. 

 Carbonatite. 



Granite. 

 Placer. 

 Carbonatite. 

 Pyroxenite. 



