150 



UNITED STATES MINERAL RESOURCES 



able thickness of 20 feet (Snyder and Gerdemann, 

 1968, p. 334). The belt contains about 500 million 

 tons of ore, if the average width of the minable zone 

 is at least 150 feet (Gerdemann and Myers, 1972, p. 

 429). If the cobalt content of the raw ore is only 0.01 

 percent cobalt, the belt contains a resource of about 

 100 million pounds of cobalt. 



Cobalt also occurs in the Wisconsin zinc district 

 that includes adjacent parts of Illinois and Iowa. 

 These ores, also of the Mississippi Valley type, in- 

 clude several cobalt minerals associated with pyrite, 

 sphalerite, and some galena and chalcopyrite. 



STRATA-BOUND DEPOSITS 



Strata-bound deposits show pronounced strati- 

 graphic localization in rocks of many different ages. 

 One metal typically dominates, generally copper, 

 lead, or zinc, and it is accompanied by lesser amounts 

 of nickel, cobalt, silver, cadmium, and other ele- 

 ments. The great copper-cobalt deposits of Zaire- 

 Zambia are of this type; they occur in folded shale 

 and dolomite that contain chalcopyrite, bornite, chal- 

 cocite, and a wide variety of other minerals, includ- 

 ing linnaeite, carrollite, and others that contain 

 cobalt. The ore bed, 20-80 feet thick, contains an 

 average of 3.5 percent copper, but some ore contains 

 2 percent copper and 2 percent cobalt. These deposits 

 currently are the world's major source of cobalt 

 (Robert, 1956). 



The copper-rich shales in the Kupferschiefer of 

 central Europe formerly produced cobalt (Andrews, 

 1962, p. 123). The cobalt, copper, lead, zinc, and 

 silver in this stratigraphic unit is a large resource 

 that currently is mostly of subeconomic value. 



CHEMICAL PRECIPITATES 



Chemically precipitated cobalt is associated with 

 the manganese nodules on the sea floor. Mero (1965, 

 p. 235) estimated that such nodules in the Pacific 

 Ocean, containing an average of 0.35 percent cobalt, 

 are a resource of 5.8 billion tons of cobalt. Copper, 

 nickel, and cobalt occur together in an average ratio 

 of 3:4:1. Thus, cobalt produced from this source 

 also would be a byproduct. (See also McKelvey and 

 Wang, 1969.) 



RESOURCES 



The cobalt resources tabulated and discussed in 

 this section have been selectively compiled from 

 various published sources. Resources outside the 

 United States were compiled only from the most 

 readily available published data. Many of the details 

 in the comprehensive compilations of world re- 

 sources of cobalt by Vhay (1952) and Andrews 

 (1962) have not been repeated here. 



The totals of resources include materials contain- 

 ing 0.01 percent or more cobalt and are expressed in 

 millions of pounds of cobalt. Resources of this grade 

 already have yielded some commercial cobalt. 



IDENTIFIED RESOURCES 



The identified resources of cobalt in the United 

 States are summarized in table 32. Most of the cobalt 

 resources of the United States potentially are avail- 

 able only as byproducts of mining for the more abun- 

 dant elements in the ores. The small production of 



Table 32. — Identified resources ' of cobalt in the 



United States 



[+ = some identified resources] 



Cobalt 

 State (millions Remarks 



of pounds) 



Alaska 125 Brady Glacier and other de- 

 posits (MacKevett and 

 others, 1971). 



Arkansas -|- Batesville manganese district. 



California 25 Chiefly laterite deposits 



(Hotz, 1966, p. 283). 



Idaho 50 Blackbird (Bilbrey, 1962, p. 



27) and Coeur d'Alene dis- 

 tricts (Vhay, 1964, p. 8). 



Maine 130 Union and other deposits 



(Young, 1968), Katahdin 

 Iron Works. 



Minnesota 1,000 Sulfide deposits in gabbro, Ely 



area (Grosh and others, 

 1955). 



Missouri 150 Southeast Missouri district 



(Kline and others, 1961), 

 Viburnum Trend (Gerde- 

 mann and Myers, 1972). 



Montana + Stillwater Complex, with 



chromium. 



Nevada + Goodsprings district. 



New Mexico 6 Blackhawk (Weber, 1965, p. 



207-209) and other dis- 

 tricts. 



North Carolina ._ 3 Chiefly laterite in the Webster 



district (Cornwall and 

 others, 1968, p. 375). 



Oregon 34 Chiefly laterite (Vhay, 1969, 



p. 116-120; Cornwall, 1966). 



Pennsylvania 66 Contact metamorphic de- 



posits in southeast region 

 (Andrews, 1962, p. 161; 

 Cornwall and others, 1968, 

 p. 375). 



Tennessee 40 Ducktown district (Magee, 



1968, p. 234). 



Vermont + Byproduct of talc operations 



(Andrews, 1962, p. 162; 

 Vhay, 1952). 



Virginia 25 Piedmont region ; gossan lead 



and also includes Sykesville 

 district, Carroll County, Md. 



Washington 20 Chiefly lateritic ores (Vhay, 



1966, p. 116-125). 



Wisconsin 10 Upper Mississippi Valley 



district, includes adjacent 

 parts of Illinois and Iowa. 



Total 1,684-1- 



1 Identified resources : Specific, identified mineral deposits that may or 

 may not be evaluated as to extent and grade, and whose contained 

 minerals may or may not be profitably recoverable with existing tech- 

 nology and economic conditions. 



