MINNEAPOLIS (AP) — A major partner gave up the right Thursday to take a bigger stake in the proposed Twin Metals copper-nickel mine near Ely in northeastern Minnesota, which has been a target of criticism from environmentalists who fear it will harm the nearby Boundary Waters Canoe Area Wilderness.

Chilean-based mining company Antofagasta PLC said it has terminated its option to buy another 25 percent of Twin Metals Minnesota LLC. The announcement said Toronto-based Duluth Metals Ltd. is now assuming control of the joint venture.