The Maine Geological Survey, part of the Department of Agriculture, Conservation and Forestry, has completed a three-year project mapping manganese-bearing rocks in Aroostook County. The initiative focused on creating detailed 1:24,000-scale geologic maps of areas near Presque Isle and Maple and Hovey mountains southwest of Mars Hill.
Manganese is an important mineral for steel production and is also used in aluminum alloys and batteries. The United States currently imports all its manganese, mainly from Gabon and Mexico. According to the Maine Geological Survey, the Aroostook County district is considered the largest manganese reserve in the country.
“This work gives us the most detailed picture ever of Maine’s manganese district,” said Maine State Geologist Dr. Ryan Gordon. “It not only advances science but also helps ensure the U.S. has reliable data on critical mineral resources.”
Although geologists have known about these manganese deposits for more than 150 years, previous mapping and exploration were last conducted about 70 years ago, before modern geological theories were established. The recent project was led by Dr. Chunzeng Wang from the University of Maine at Presque Isle and resulted in three bulletins with reports and maps covering the Presque Isle, Mapleton, and Number Nine Lake map quadrangles.
Funding for this effort came from the U.S. Geological Survey’s Earth Mapping Resources Initiative (Earth MRI), which aims to update geologic data related to critical minerals across the United States. These minerals are vital for economic stability, clean energy development, and national defense but face risks due to dependence on foreign supply chains.
