Just before Christmas, the Department of the Interior reversed an Obama administration decision and opened the door for a copper-nickel mine near the Boundary Waters Canoe Area Wilderness in the northeast Arrowhead region of Minnesota. ... Northeastern Minnesota is known as the Iron Range and taconite mining is deeply tied to its history. But Twin Metals, the Minneapolis-based company that holds the leases, is planning an underground copper-nickel mine, which has never been tried in t