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

INTRODUCTION

Coal is the most abundant fossil fuel in the United States. Knowledge of the size, distribution, and quality of the Nation's coal resources is important for governmental planning; industrial planning and growth; the solution of current and future problems related to air, water, and land degradation; and for meeting the short- to long-term energy needs of the country. Knowledge of the Nation's coal resources is also important in planning for the exportation and importation of fuel.

Many estimates have been made of the coal resources of the Nation, the resources of other nations, and for the world as a whole. Because of differing systems of resource classification, these estimates vary greatly in magnitude within this Nation and other nations; geologic analysis shows some of these estimates to be little more than educated guesses. The accompanying coal resource classification system of the U. S. Geological Survey is recommended as an aid in solving the problems caused by the differing systems.

A detailed resource classification system should identify deposits of coal by areal location, distance from points of information, thicknesses of coal and overburden, rank and quality, and estimates of quantity. Classes in the system, furthermore, should impart some idea as to economic, technologic, legal, and environmental factors affecting the availability of coal. A coal resource classification system was published jointly by the U.S. Bureau of Mines and the U.S. Geological Survey in 1976 as Geological Survey Bulletin 1450-B and was believed to be a successful modification of an already existing system into the ideal system. However, Bulletin 1450-B left unanswered many questions concerning how to estimate coal resources and did not provide sufficient criteria, guidelines, and a methodology so that comparable estimates would be obtained by all workers using the same data.

The Survey and the Bureau of Mines decided in 1977 that the coal resource classification system, as outlined in Bulletin 1450-B, should be revised and expanded to provide a more definitive and less ambiguous coal resource classification system. The revision was to document standard definitions, criteria, guidelines, and methods to be used in estimating coal resources. Standardization of the elements of the system should result in comparable estimates by different workers using the same data.

In 1980, the two agencies published Circular 831, "Principles of a Resource/Reserve Classification for Minerals" (U.S. Geological Survey, 1980). The circular, which outlines a classification system for all mineral commodities, filled the classification needs of the Bureau of Mines, which was no longer responsible for coal resource classification, and was the basis for this revision of the coal resource classification system by the Geological Survey. The revision, embodied in this report, has two main objectives: (1) to provide detailed information lacking in Bulletin 1450-B; and (2) to provide standard definitions, criteria, guidelines, and methods required for uniform application of the principles outlined in Circular 831.

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