The Indiana coal field forms the eastern edge of the eastern interior coal basin, which is near some of the most densely populated and highly productive manufacturing areas of the United States. (See fig. 1. ) For this reason Indiana coal reserves are an important State and National asset.
In dollar value the coal mining industry is the largest of Indiana's natural-resource-producing industries. The total value of coil production for the year 1950 was more than 100 million dollars, or more than that of all other natural-resource industries in the State combined.
As estimated herein, the original coal reserves of Indiana total 37,293 million tons, of which 27,320 million tons is contained in beds more than 42 inches thick; 7,632 million tons in beds 28 to 49. inches thick; and 2,341 million tons in beds 14 to 28 inches thick. The remaining reserves as of January 1951, total 35,806 million tons, of which 18,779 million tons is believed to be recoverable. The distribution of the reserves in these several categories is summarized by counties in table 1.
Of the total original reserves of 37,293 million tons, 6,355 million tons can be classified as measured; 8,657 million tons as indicated; and 22,281 million tons as inferred. Strippable reserves constitute 3,524 million tons, or 9.5 percent of the total original reserves. The distribution of the strippable and nonstrippable original reserves is summarized in tables 2 and 3 by counties and by several categories, according to the thickness of the beds and the relative abundance and reliability of the information available for preparing the estimates.
The distribution of the estimated 18,779 million tons of recoverable strippable and nonstrippable reserves in Indiana is further summarized by counties in table 4, and the information is presented graphically in figures 2 and 3.
The tables i to 4 and figures 2 and 3 include beds in the 14- to 28-inch category, because thin beds have been mined in many places. However, many operators prefer to eliminate the thin beds from consideration as reserves, particularly for deep mining. It is notable, therefore, that only a small part of the estimated reserves in Indiana is contained in the thinner beds. Of the total estimated, recoverable reserves of 18,779 million tons shown in table 4, only 1, 233 million ton's, or about 6 percent, is contained in beds less than 28 inches thick, whereas 17,546 million tons, or about 94 percent, is contained in beds more than 28 inches thick.