Purchase first-rate mined aggregates from Northern Con-Agg. Our small, family-owned company produces sand and gravel aggregates and kaolin clay from our mines in Rauville, South Dakota, throughout the state and other locations in Minnesota. Our owner came from the paving business but decided to get into aggregate mining and Northern Con-Agg was born. The company began operations in 1986 as an aggregate producer with locations in Minnesota and South Dakota. Today, Northern Con-Agg, LLP continues with the tradition of more than 30 years of aggregate and kaolin mining experience.