Testing Of Selected Samples From Mapping Of Industrial Clay Potential In The Minnesota River Valley, South-Central Minnesota

Abstract

As part of the mapping of industrial clay potential in the Minnesota River Valley (MRV) and Cottonwood River Valley (Zanko et al., 1998), 94 samples were collected for reference and future analysis. The primary focus of that study was to outline areas of potential for industrial clays, primarily kaolins, and ball clays, based on field observations and examining the water well logs for the area. The mapping project’s goal was to produce a GIS-based reference tool for land-use planning and clay exploration. This study was conducted to analyze 27 selected samples from Area 10 of Zanko et al. (1998), along the Cottonwood River in Brown County, Minnesota. This area was selected for additional work, based on field mapping, because of the high potential for the delineation of useful industrial clays. The lack of analytical data about the clays in this area made determining the potential of the area difficult. The clays included in the study are largely Cretaceous in age, Cretaceous sediments, and secondary sediments (Zanko et al., 1998), and a sample of an uncertain age, possibly a weathered Paleozoic shale. Most of these clays formed from the weathering and reworking of crystalline Archean bedrock, along with mineral contributions from weathered Paleozoic bedrock in the southeastern part of the study area. Similar Cretaceous clays are currently mined by the Ochs Brick and Tile Company, Springfield, Minnesota, and Minnesota Valley Minerals Inc., Mankato, Minnesota, for use in brickmaking and artistic ceramic clays. Other industrial clays in the area come from primary kaolin deposits, clays which formed in place from the intense weathering of crystalline Archean bedrock. No samples of primary kaolins are included in this study, but they do make up the largest tonnage of industrial clays mined in the MRV area, and are dominantly used in the production of portland cement.