By Nicole Rashotte Japan’s Sumitomo (TYO:8053) has purchased a 5-percent stake in the Yanacocha gold mine in Peru for US$48 million in order to boost its metals portfolio, the company announced on Thursday (June 21). Yanacocha has been in production since 1993 and was once Peru’s largest gold mine. In recent years, production has declined but Sumitomo believes in its growth potential, as the life of mine could possibly be extended to 2039 and it also contains copper deposits.