Metallic Mineral Deposits of Maine

map of significant metal deposits
Metallic Mineral Deposits of Maine (PDF 0.7MB)

The Metallic Mineral Deposits of Maine map (PDF 0.7MB) shows locations of known metallic mineral occurrences on a generalized geologic map of Maine. The information is taken from the Maine Mineral Resources database of the Maine Geological Survey. That database includes more information about the occurrences that are shown on the map, and also includes many non-metallic mineral occurrences, which are not shown on this map.

The vast majority of occurrences on this map, shown by red dots, have not been explored or investigated to any great extent. A significant amount of investigation over many years would be required to know whether any of these occurrences might represent a mineral deposit of any size, and if so, what the composition, metal content (grade), nature, and extent of any such deposit might be. It is best to consider these red dots as possible targets for further exploration. One thing to notice is that there are occurrences of metallic minerals in many different geologic settings and in many areas of the State.

Twelve occurrences, shown on the map by stars, are considered to be significant deposits. The ten shown by yellow stars have been explored geologically to various degrees. The two shown by blue stars are the only metallic mineral deposits in Maine that have been mined in the past half-century. The back page of the map lists some of the general characteristics of each of these twelve deposits. This information has been estimated on the basis of what is currently known for that deposit. [Except for the Pickett Mountain deposit, none of these estimates would qualify as modern resource estimates under current requirements of Canadian National Instrument 43-101, the industry standard for reporting scientific and technical information about mineral deposits.] Of the twelve significant deposits indicated, nine are massive sulfide deposits. Of these, the Bald Mountain deposit, discovered in 1977 by John Cummings with Northeast Joint Venture, is the largest by an order of magnitude, and had been explored most extensively until the recent work at Pickett Mountain. The Maple-Hovey deposits, though large in tonnage, are a fundamentally different type of deposit, occurring in long, thin layers extending for some distance, in contrast with the more localized massive sulfide deposits, and containing manganese and iron oxide minerals rather than copper, lead, zinc, or nickel sulfide minerals. The lithium deposit at Plumbago North is hosted by a spodumene-bearing granitic pegmatite. The recently discoverd zone of highly mineralized rock east of Pennington Mountain is yet another type of deposit, apparently formed by hydrothermal alteration of volcanic rocks.

Last updated on April 12, 2023