1 Exhibit 21 MEDUSA CORPORATION AND SUBSIDIARIES Exhibit 21 to Form 10-K Subsidiaries of the Registrant December 31, 1997 The following is a list of active subsidiaries of the Registrant and their jurisdiction of incorporation. All of these subsidiaries are wholly-owned, directly or indirectly, and are included in the consolidated financial statements. Cement Transit Company Delaware James H. Drew Corporation Indiana Medusa Aggregates Company Iowa Medusa Minerals Company Maryland Canadian Medusa Cement Limited Ontario, Canada Medusa-Citadel, Inc. Alabama Medusa-Crescent, Inc. Pennsylvania Medusa Aggregates LLC Pennsylvania Medusa Portland Cement Company Michigan Medusa Minerals Co. - Lee Delaware Medusa Minerals Co. - Sparta New Jersey White Stone Company of Southwest Virginia Virginia Clinch River Quarries, Inc. Virginia