A mining company exploring copper and nickel deposits southeast of Ely will update its estimate later this month. Twin Metals has drilled more than 400 holes as it puts together a picture of the deposits. One industry expert tells MPR it's already clear there's enough precious metal to keep mines busy for 60 years. The debate over whether to issue environmental permits is in the early stages, though, and any mines are still years away.

Twin Metals wants to build the largest mine in Minnesota history -- a project on par with the biggest mines in the world -- to tap into what geologists say are enormous metal deposits. The Duluth News Tribune says it would be among the most extensive private enterprises in state history.

The Associated Press reports new technology will allow miners to reach down nearly 4,000 feet into the earth to tap into possibly one of the largest untapped nickel and copper mines in the world. Twin Metals executives say the project will bring thousands of new jobs to the Iron Range.

Critics warn new copper and nickel mines will harm northeastern Minnesota's land and water. But St. Louis County commissioners sided with those who say mining can be done well and bring economic prosperity.

Mining companies from around the world are exploring what lies under northeastern Minnesota and are finding some of the largest copper deposits on the planet. Minnesota's lode is estimated at 900 million tons, which would be second only to Russia. With economic growth - especially in China - pushing up demand for copper and other metals, Minnesota is poised for a resurgence of well-paying mining jobs.