Coal Resource Classification System of the U.S. Geological Survey
By Gordon H. Wood, Jr., Thomas M. Kehn, M. Devereux Carter, and William C. Culbertson
GEOLOGICAL SURVEY CIRCULAR 891
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| Figure 2 - Format and classification of coal resources by reserve and inferred reserve bases and subeconomic and inferred subeconomic resources categories |
Created by the EERT WWW Staff.
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