Arcosa Specialty Materials (Harrison Gypsum, ACG Materials) mines, mills, processes, and distributes minerals and aggregates. But here, it's more than just about the products. It's about providing a level of service that surpasses customer expectations, far beyond what they may receive anywhere else. With a legacy of professional quality and service dating back to 1955, AGC Materials has earned the industry respect of our customers from the smallest organizations to Fortune 500 companies.