In 1988, ninety ground-water samples were collected in northern Daviess County, Indiana. Sampled wells were completed in the Pennsylvanian Age Racoon Creek Group and underlying Mississippian units. Twenty-one inorganic parameters were targeted for laboratory analysis.The computer program DATAGEN4 was utilized to generate saturation indices for target mineral species. Thirteen, thirty-six, twenty-four, eighty-six, and thirteen samples were saturated with barite, calcite, dolomite, hematite, and siderite, respectively. All samples were undersaturated with respect to gypsum and fluorite.Trilinear diagrams were plotted, and the prevalent chemical characters of the samples were determined. Generally, samples collected from depths of less than 225 feet were characterized as Ca-HCO3 waters. Deeper wells yielded Na-HCO3 and Na-HCO3-Cl type waters.The naturally-occurring chemical processes that result in the water types (decomposition of organic material, carbonate dissolution, and cation exchange) are described. The influence of coal units and upwelling brines on ground-water chemistry is also discussed. / Department of Geology