Kasota limestone
Kasota limestone or simply, Kasota stone, also called Mankato stone, is a dolomitic limestone found in southern Minnesota, especially near the Minnesota River and its tributaries. This sedimentary rock is part of the Oneota Dolomite of southern Minnesota and is approximately 450 million years old (lower Ordovician Period). This particular limestone is rich in dolomite and magnesium, making it resistant to weathering, and it is thus widely used as a building material. Its name is taken from Kasota Township where the stone has been quarried.