Martin Marietta Materials is a natural resource-based building materials company. Co. supplies aggregates (crushed stone, sand and gravel) through its network of quarries, mines and distribution yards. Co. also provides cement and downstream products, namely, ready mixed concrete, asphalt and paving services. Co. conducts its Building Materials business through three segments: Mid-America Group, Southeast Group and West Group. The Mid-America and Southeast Groups provide aggregates products only. The West Group provides aggregates, cement and downstream products. Co. also has the Magnesia Specialties segment, which includes its magnesia-based chemicals and dolomitic lime businesses.