Characterization of the Kaolin Occurrences in Northern and Central Minnesota

Abstract

Kaolin mining and exploration in Minnesota has been concentrated in the Minnesota River Valley, in the south-central part of the state. Potential exists for kaolins in northern and central Minnesota. Using the resources of the Minnesota Department of Natural Resources Drill Core Repository, over 1,250 drill logs were reviewed for references to kaolin bearing materials. This process resulted in 170 drill holes that contained references to kaolin bearing materials. Examination of these drill holes resulted in the selection of 60 drill holes containing kaolinitic materials for detailed logging. Detailed logging resulted in the collection of 287 samples from 40 drill holes. All samples were run for particle size analysis, and 27 selected samples were run for geochemistry. Many regions in the study area show potential for kaolin clay exploration. All areas sampled have favorable geochemistry and particle size analyses for current industrial clay uses, which include brick manufacturing, ceramics, and portland cement production. The areas with the greatest potential are Cass, Crow Wing, Stearns, Chippewa, Lac Qui Parle, and Pope Counties. Other possible uses for these clays include, refractory materials, fillers and pigments for industrial and agricultural applications, and coating and fillers for the paper industry. Exploration for kaolin deposits may be hindered by the lack of outcrop and thick overburden in some of these areas. The use of geophysical techniques, coupled with the examination of other drill holes and water well log data, may aid in the location of areas of further interest for exploration companies.