MINERALS OF THE UNITED STATES — PEHRSON 183 



with the original reserve, which was determined by adding the total 

 production through 1943 to the reserve estimates as of January 1, 

 1944. The chart includes 25 of the major industrial minerals for 

 which reasonably reliable estimates can be made. It does not include 

 building materials, with which the United States is amply supplied, 

 nor does it include some important minerals of which the United 

 States is notably deficient, such as tin and nickel. 



Outstanding features of the chart are the relatively favorable po- 

 sition in coal and the fertilizer materials, and the relatively depleted 

 state of our metallic reserves. There has been no exhaustion of the 

 original reserve of magnesium and nitrogen, the supplies of which 

 are virtually inexhaustible, because of the abundance of brines and 

 ocean water from which we obtain magnesium, and of air from which 

 we extract nitrogen and other valuable elements. Air and water are 

 two minerals whose importance should not be overlooked although, of 

 course, they present no reserve problem. At the other extreme is 

 mercury, of which it is estimated that only 3 percent of the original 

 commercial reserve remains. This metal presents an interesting il- 

 lustration of the relation of production and price. Production reached 

 a peak as far back as 1877, when the United States was supplying most 

 of the world. Since the last war we have been heavy importers yet the 

 stimulus of high war prices — over four times those of 1877 — has 

 brought forth a surprisingly large output in the last few years. The 

 percentages shown for natural gas and petroleum are based on proved 

 reserves only, which tends to exaggerate the depletion that has taken 

 place in these industries. The exhaustion indicated for antimony, 

 manganese, and chromium are of nominal significance only in view of 

 the fact that domestic resources have not made important contribu- 

 tions to national requirements as will be shown later. Somewhat more 

 significant is the situation shown for tungsten, vanadium, and bauxite, 

 although we also have been large importers of these materials in the 

 past. The position of iron ore is a matter of some concern from the 

 long-range view because of its essentiality to our industrial structure. 

 Of more immediate concern is the depleted state of our copper, lead, 

 and zinc resources and it is also apparent that we have drawn exten- 

 sively on our commercial reserves of gold and silver. 



RESERVES COMPARED WITH PREWAR CONSUMPTION 



Figure 5 shows the estimated commercial reserves of various min- 

 erals in terms of years' supply at the average annual rate of consump- 

 tion from 1935 to 1939. The data should not be interpreted as indi- 

 cating that production large enough to meet the prewar rate of use 

 could be sustained for the periods indicated. Many of the minerals 

 shown are not now being produced in quantities equal to domestic 



