Gypsum and Anhydrite Deposits in Southwestern Indiana

Abstract

This investigation was undertaken to make the features of evaporites (gypsum and anhydrite) in southwestern Indiana known and to determine their origin, geologic occurrence, uses, and relationship to associated rock strata. A detailed study of evaporites in Indiana has never been undertaken. In fact, it was not known until recently that relatively thick beds existed in the state. Evaporites, however, are not new among the minerals found in Indiana; they have been observed in well cuttings and as nodular masses and thin beds in outcrops. Logan reported that a thin bed of gypsum (selenite) crops out between the Beaver Bend limestone and Sample sandstone in a railroad cut east of Huron, Lawrence County. Gypsum also occurs commonly as nodular masses in the Harrodsburg and St. Louis limestones and in many places forms a conspicuous part of their lithology. Moreover, as stated above, subsurface studies in southwestern Indiana have revealed rather extensive gypsum deposits in the lower part of the St. Louis limestone.