COEUR d’ALENE — Hecla Mining Co. has reached a nearly $30 million deal to acquire Mines Management Inc., the owner of the Montanore Mine in northwestern Montana, company officials announced Tuesday.

In the proposed merger, each outstanding common share of Spokane-based Mines Management will be exchanged for 0.2218 of a common share of Hecla Mining, which is based in Coeur d'Alene, Idaho. Mines Management shareholders still must approve the deal.

"The Montanore Project has been significantly advanced by Mines Management and, with the issuance of the final Environmental Impact Statement and Records of Decision early this year, now is the time to pass it on to Hecla to further advance the project and put it into production," said Glenn Dobbs, CEO and Chairman of Mines Management.

Luke Russell, Hecla spokesman, said with the record of decision in hand, the company will now enter into an evaluation of the Montanore by assessing its geo-hydrology and finishing driving the adit, or main tunnel, into the ore body.

Russell said the main adit is about 14,000 feet into the mountain and needs to go another 3,000 feet to the ore body.

Once Hecla confirms the economic feasibility of the mine, Russell said the company will begin constructing the infrastructure needed to bring the mine into full production.

“We are looking at full production sometime around 2025 to 2030,” Russell said.

Hecla already owns the Rock Creek Mine, which is also under Montana's Cabinet Mountains Wilderness, and about 10 miles away from Montanore. Hecla also owns the Lucky Friday Mine in Idaho, which is about 50 miles from Montanore.

"Hecla is the logical company to move the Montanore forward, with its close proximity to Rock Creek, as well as its similar geology and scale," Phillips S. Baker Jr., Hecla's president and CEO, said in a statement.

Russell said the Rock Creek Mine has filed for a supplemental Environmental Impact Statement and is going through a similar process as the Montanore project, and he expects to see Rock Creek coming up to full production in roughly the same time frame.

The U.S. Forest Service has given its conditional approval to the Montanore Mine, but the mine still needs a water pollution permit from the Montana Department of Environmental Quality. DEQ Director Tom Livers has said mine officials need to show the mine won't degrade five nearby creeks and the East Fork of the Bull River. The mine also needs a permit from the U.S. Army Corps of Engineers.

Last month, environmental groups filed a lawsuit arguing the Forest Service ignored studies that found the Montanore Mine could drain groundwater supplies in the area, damaging the habitat of federally protected bull trout.

Mines Management estimates the Montanore deposit contains 230 million ounces of silver and 2 billion pounds of copper. The mine would disturb more than 1,500 acres and remove up to 120 million tons of ore. Its entrance would be just outside the wilderness area — a rugged, remote landscape and one of a handful of areas in the United States where the government is seeking to restore grizzly bear populations.

Hecla Mining shares were down about 19 cents to $4.05 Tuesday morning, while Mines Management shares were up 23 cents to 87 cents a share.