The earliest operation of mining of bog iron in Maine began in Newfield but was a small scale operation but it continued for a long period of time. During the mid 1880’s the other enterprises were near Lubac, that was a lead mine and Katahdin Iron Works. There was a mining boom from 1879 to 1882 that led to the opening of many mines during this time especially near the coastal volcanic belt from Blue Hill to Lubec and various minerals such as iron, silver, copper, lead, and zinc were mined, milled, concentrated, and smelted.

The prices dropped in 1883 and so a lot of mines had to be closed and the mining activity was irregular till 1918 after which the production of base metals in Maine stopped for almost 50 years, however an intensive exploration programs for manganese were launched by the US and Maine governments during World War II.

Manganese was an element that was placed on the strategic list of the war department and it was discovered in Aroostook County in the mid 1800’s and from this, it is clear that manganese is available in huge amounts, however ore has never been mined due to the unavailability of the efficient processes that are involved in extracting the mineral. In 1950’s, another exploration program was started and large amounts or ore were found near Bathurst, New Brunswick, however most of the attention was still given to the coastal volcanic belt but the inland volcanic belt from northwestern to northern Maine was also examined.

In 1964 and 1965, ore worth 4. 5 million tons was worked near Blue Hill and an important nickel-copper deposit in Union was discovered and drilled but not mined. The most famous operation was at the Harborside mine and this was situated between Brooksville and Cape Rosier, moreover it produced 800,000 tons of copper and zinc ore from 1968 to 1972. Black Hawk mine near Blue Hill was the largest producer, it was an underground mine and in 1972 and 1977, it produced an estimated 1,000,000 tons of zinc-copper-lead ore, however metals were not mined in Maine since 1977.

It was in the mid 19970’s to early 1990’s when a high level of exploration began and resulted in the discovery of many important minerals and from these, Ledge Ridge deposit in Parmachenee in 1973 was one of the most important discoveries as it produced million tons of zinc, lead, copper and the Bald Mountain deposit west of Portage in 1977.

This was basically a large massive copper-zinc sulfide deposit with an estimated 36 million tons of ore. The Mount Chase copper-lead-zinc-silver deposit in 1979 and the Alder Pond deposit in 1985 had underground minerals that ranged from 1. 5 to 3 million tons of high grade copper-zinc ore and although there is a chance that these sites would be developed in the future but they have not been mined yet.