Abundant black organic-rich shales occur in rocks of Pennsylvanian age in southwestern Indiana. They have not been well characterized except for a few thin intervals in small areas, the best example being at the abandoned Mecca Quarry in west-central Indiana. Although these shales are thinner and less widespread than the organic-rich shales of the New Albany Shale (Devonian and Mississippian age) they warrant characterization because of their accessibility during strip mining of underlying coals.

Organic-rich shales of Pennsylvanian age contain up to 44% organic carbon and might be considered potential oil shales. Carbon to hydrogen ratios in these shales are similar to those in the New Albany. Relatively high concentrations of certain metals occur in shales of both ages, especially where phosphate is abundant, and sulfur values for both shales

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range from < 1 to 6%. Sulfur values are much higher for thin pyrite-rich units. Siderite nodules are common in Pennsylvanian shales, but little siderite is found in the New Albany. Dolomite, commonly ferroan, and calcite in a variety of forms are the dominant carbonates in the New Albany. Some Pennsylvanian shales may contain large fossils or mica flakes, but such coarse-grained features are uncommon in the New Albany Shale.

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