190 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1945 



that imports will remain at the same proportion as in the past, the 

 iron-ore requirements in 1970 total between 95,000,000 and 115,000,000 

 long tons. Maximum production to date was 105,526,000 tons in 1942. 



While the total iron-ore reserves appear to be ample to meet domestic 

 requirements for a prolonged period, we shall soon be confronted with 

 a major problem because of the exhaustion of the direct-shipping ores 

 of the Lake Superior district, found chiefly in the Mesabi Range in 

 Minnesota. This ore represents the cream of our resources because 

 the deposits can be mined cheaply and the ore used directly in the blast 

 furnace without prior treatment. Direct-shipping ores of Minnesota 

 account for 50 percent of the total production of the country. At the 

 1942 rate of extraction the remaining tonnage represents only 17-years' 

 life, and the rate of production will begin to decline in the near future. 

 The problem is made more acute because 90 percent of the production 

 of these high-grade Minnesota ores come from the open-pit mines that 

 contain only 57 percent of the reserves. Exhaustion of these mines 

 is therefore rather imminent. Declining rates of production at the 

 open-pit mines can be offset only in part and for only a few years by 

 increasing the output of direct-shipping ore from underground mines 

 and concentrates. The total estimated reserves of commercial-grade 

 ore in the Lake Superior district is equivalent to less than 25-years' 

 life at the current rates of production. It is therefore obvious that 

 if the district is to continue to supply large tonnages, development of 

 the low-grade ores must be started in the near future. 



The open-pit mines provide great flexibility in production because 

 mining can be stopped completely if necessary with low maintenance 

 costs and little adverse effect on production capacity, and it can be 

 increased quickly in periods of heavy demand. During the present 

 war this resource has been of inestimable value in making possible 

 our enormous steel output. The impending loss of this facility is 

 thus a matter of major national interest because it has served as a 

 gigantic stock pile which has supplied the needs of the Nation in times 

 of heavy demand and national emergencies. If we are to become 

 dependent on our lower-grade ores we shall have to build large plants 

 to treat them. Such plants provide rigid limits on production capacity 

 and if surplus capacity is maintained to meet peak demand, deprecia- 

 tion and obsolescence on a large scale will have to be reckoned with. 



Failure to develop the low-grade ores of the Lake Superior district 

 eventually would lead to dependence on foreign sources of supply. 

 In view of the large tonnages required, the maintenance of shipments 

 from foreign sources in time of war would present a major problem 

 of national defense. Because of this and the high essentiality of steel 

 in war, it would seem unwise for the United States to allow its self- 

 sufficiency in iron ore to fall to dangerous limits. Presumably to 

 maintain our present position would justify some extra cost to the 



