Northeast Arm Iron Range

The Northeast Arm Iron Range runs along the western shore of Lake Temagami and displays alternating layers of iron-rich and iron-poor sediments. These formations are part of the Temagami Greenstone Belt and show how rock structures developed over deep time.

Mining began at Sherman Mine in 1968 as a partnership between Dofasco and Tetapaga Mining Company, processing ore from this site. Operations stopped in 1990 after decades of extracting and processing materials from the iron formation.

The iron range development brought diverse mining communities to the Temagami area, influencing the regional economic structure of Northeastern Ontario.

You can view the iron formations from Highway 11, where marked access points allow closer geological study. The rocks are most visible during drier periods when water levels are low.

The iron formation holds deposits of chert, jasper, and magnetite that came from ancient hydrothermal vents. These minerals took shape in an ocean that existed billions of years ago.

Location: Ontario

GPS coordinates: 47.05692,-79.84684

Latest update: December 12, 2025 14:23