340 



UNITED STATES MINERAL RESOURCES 



FOjOj, FeO. S 

 CaO, MgO, Pj Oj 

 Na, O, K,0, NO, 



EXPLANATION 

 Bloater 



Nonbloater 



Reference 



Riley (1951) • o 



White (1960) A ^ 



Sweeney and Hamlin (1965a) ■ d 



Figure 41. — Comparative composition of bloating and nonbloating argrillaceous rocks. 



the continental United States. The Hst of suitable 

 rocks in the Appalachian region as given by Bush 

 and Sweeney (1968) illustrates the number and 

 variety available and is probably not complete. 



The sheer volume of suitable rocks make reserve 

 and resource problems somewhat different from 

 those for most mineral commodities. The distinctions 

 among proved, probable, and possible reserves are 

 somewhat blurred, inasmuch as the principles of 

 stratigraphic continuity allow for projection of the 

 favorable unit for unusually great distances beyond 



points of observation, but the amount of accuracy 

 in the calculation of tonnage is fair. In most min- 

 eral deposits, paramarginal and submarginal re- 

 serves are in lower grade, larger tonnage masses 

 for which a complex interplay of costs determines 

 profitability. In this situation the entire rock mass 

 is the ore, changes in processing technology are sel- 

 dom involved, and transportation costs are usually 

 the determining element in separating recoverable, 

 paramarginal, and submarginal reserves. The dis- 

 tinction between hypothetical and speculative re- 



