MADISON, Wis. — A mining company has gotten conditional approval to begin exploratory drilling for copper and gold in northern Wisconsin, but state regulators say it must still meet additional requirements before the work can begin.

Canadian company GreenLight Metals, doing business as Green Light Wisconsin, wants to conduct exploratory drilling at a 40-acre site owned by the U.S. Forest Service about 20 miles northwest of Medford in Taylor County. The deposit is believed to contain 4 million tons of mostly copper and gold.

The Wisconsin Department of Natural Resources last week authorized the company’s plans to drill up to eight holes impacting less than an acre of the Chequamegon-Nicolet National Forest, Wisconsin Public Radio reported today.

Mining company Aquila Resources last conducted drilling of the deposit in 2012, which was first explored in the early 1990s.

Green Light has said it expects work to be conducted in phases and last about 10 weeks. Once work commences, the company must comply with detailed conditions for wetlands and waterways, erosion control and endangered resources at the site. It must also document its work.

Metals like gold and copper that occur in sulfide ore bodies have not been mined in Wisconsin since the Flambeau mine shut down in 1997. Concerns over pollution related to that mine led to the state’s sulfide mining moratorium that was repealed in 2017 under a law passed by the Republican-controlled state Legislature.