Abstract

Three new wurtzite-type polymorphs of ZnS have been found along shrinkage cracks in clay-ironstone concretions a few feet above the Brush Creek limestone horizon of the Conemaugh Formation near Etna, Allegheny County, Pennsylvania. Two of them, wurtz-ite-4H and wurtzite-6H, have been noted at this horizon over an area of fifty square miles in western Pennsylvania and eastern Ohio. The third, wurtzite-15R, is reported in only four crystals from the Etna locality. The geology and mineralogy are described for the known occurrences of these polymorphs.

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