178 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1945 



Figure 3, which shows the dollar value of imports and exports of 

 minerals and mineral products, indicates that we have been generous 

 in making our minerals available to the rest of the world. Foreign 

 trade figures include some semifabricated products the dollar value 



■~ z 



240 



220 - 



1900 



1905 



1910 



1915 



1920 



1925 



1930 



1935 



1940 



1945 



Figube 2. — Comparison of growth of physical volume of mineral production with 

 that of agricultural and industrial production and population, 1900-44. 



of which per unit of mineral is relatively high compared with that of 

 raw materials. The values shown in the chart, therefore, are not 

 directly comparable with those given for mineral production. 



NEED FOR APPRAISAL OF MINERAL RESERVES 



The unprecedented rate at which we have been depleting our min- 

 eral resources and the difficulties encountered in obtaining sufficient 



