140 



UNITED STATES MINERAL RESOURCES 



future planning for the utilization of all energy 

 resources. 



SPECULATIVE RESOURCES 



The resources presented in table 27 and discussed 

 under the headings of identified and hjrpothetical 

 resources represent total resources within limits 

 established by the minimum thickness of coal beds 

 and the maximum thickness of overburden. The 

 major geologic features of the United States are 

 known well enough to justify the statement that, 

 in all probability, no major coal fields remain to be 

 discovered. Hence the coal resources of the United 

 States are all either identified or hypothetical. Be- 

 cause there are no undiscovered districts, there are 

 no speculative resources. 



WORLD COAL RESOURCES 



The original identified coal resources of the world 

 total about 9,500 billion tons, the additional hypo- 

 thetical resources total about 7,330 billion tons, 

 and the two categories combined total 16,830 billion 

 tons. The distribution of this tonnage by continents 

 is shown in table 28. 



Table 28. — Estimated total original coal resources of the 

 world, by continents ^ 

 [In billions of short tons] 



Hypothe- Estimated 

 Continent Identified tical re- total 



resources ^ sources ^ resources 



Asia' '7,000 4,000 '11,000 



North America 1,720 2,880 4,600 



Europe 620 210 830 



Africa 80 160 240 



Oceania 60 70 130 



South and Central 



America 20 10 30 



Total '9,500 7,330 "16,830 



^ Original resources in the ground in beds 12 in. or more thick and gen- 

 erally less than 4,000 ft below the surface, but includes small amounts 

 between 4,000 and 6,000 ft. 



^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. 



^ Hypothetical resources : Undiscovered mineral deposits, whether of 

 recoverable or subeconomic grade, that are geologically predictable aa 

 existing in known districts. 



* Includes European U.S.S.R 



5 Includes about 6,500 billion short tons in the U.S.S.R. 



'Includes about 9,600 billion short tons in the U.S.S.R. (Hodgkins, 

 1961, p. 6). 



The figures for the United States as shown in 

 table 27 are included in the total for North America 

 in table 28. On the basis of identified resources, the 

 United States contains about one-sixth of world 

 resources ; on the basis of total resources, the United 

 States contains about one-fifth of world resources. 



Table 28 shows clearly that Asia contains most 

 of the world's total coal resources. This tonnage is 

 concentrated in the U.S.S.R. and China, both of 

 which are important coal-producing countries. The 



table also shows that the coal resources of Europe 

 have been well established by mapping and explora- 

 tion, and that estimates will not be greatly increased 

 by future work. Finally, table 28 shows that Africa, 

 Oceania, and South America contain small re- 

 sources as compared with the rest of the world, but 

 that the quantities assumed to be present are suffi- 

 cient to justify continued exploration and develop- 

 ment. (See Averitt, 1969, p. 81-85.) 



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