Coeur d’Alene-based Hecla Mining Co. said this morning that it has agreed to acquire Mines Management Inc., of Spokane.

The transaction is expected to be completed during the third quarter of 2016 and is subject to approval by Mines Management shareholders.

Under the terms of the agreement, Mines Management shareholders will receive 0.2218 common shares of Hecla for every one share of Mines Management.

Once the transaction is finalized, Hecla plans to evaluate Mines Management’s Montanore project, which is located in northwestern Montana and is considered one of the largest undeveloped silver and copper deposits in North America. The proposed mine is about 10 miles from Hecla’s Rock Creek project and 50 miles north of its longtime Lucky Friday Mine, near Wallace, Idaho.

Mines Management President and Chairman Glenn M. Dobbs had said last December that it would cost about $500 million to start excavating the site and that the company was looking at whether to try to develop it, to enter into a joint venture to develop it, or to sell it.  

Late last year, the company had said it was back in the good graces of the New York Stock Exchange after facing an ultimatum either to come back into compliance with exchange rules or risk being delisted.

The company on July 1 received notice from the NYSE that it was in danger of being delisted because it had failed to meet certain listing standards. Specifically, it had reported losses for the five most recent fiscal years and stockholders’ equity had fallen below acceptable levels, the NYSE said.

To generate additional cash and keep operating, Mines Management sold some of its assets last October and raised $1.25 million to continue the permitting process for the Montanore project.

Hecla’s announcement of its plans to acquire Mines Management comes less than a year after it acquired another Spokane-area mining concern, Revett Mining Co. It completed its acquisition of Revett in June of 2015 and took over its Rock Creek project then.