The 125-year-old Kasota Stone plant in Mankato is closing. 4th-generation owner Robert Coughlan says they’ve probably kept the business going longer than they should have for sentimental reasons, and that the closure is tough. More than two dozen employees have been laid off or have found work with another Coughlan family business. Besides cutting dimensional limestone from the quarries for building construction, Coughlan also leases quarry space to a company that breaks stone into aggregate. That operation will continue. Mining is Mankato’s oldest industry. Its first quarry opened a year after the town was founded in 1858.