Beginning of Commercial Production by Sierra Gorda Copper Mine Project in Chile

Sumitomo Metal Mining Co., Ltd. ("SMM", Head office: Minato-ku, Tokyo; President: Yoshiaki Nakazato) and Sumitomo Corporation ("SC", Head office: Chuo-ku, Tokyo; President: Kuniharu Nakamura) announced that Sierra Gorda SCM (the project company of the Sierra Gorda Copper Mine Project, Head office: Santiago, Chile), which is jointly owned by SMM, SC and KGHM Polska Miedź S.A. ("KGHM"), a major Polish copper producer (SMM, SC and KGHM own 31.5%, 13.5% and 55% interests respectively), and which completed construction in 2014 and started to produce Copper Concentrates and Molybdenum Concentrates, began commercial production which is based on the criteria that the copper plant has been operating for over 60 days at 65% of its designed capacity and the molybdenum plant has produced molybdenum concentrate with at least 40% molybdenum content at the end of June 2015.

Sierra Gorda SCM will continue through the ramp-up stage and then carry out, the long-term and stable operation for over 20 years life of mine.