March 2011

Rock Face At Cranberry Iron Mine

The rock face of the upper opening at the Cranberry Iron Mine shows some nice colors. I suspect a much of it is rust because of high iron content of the magnetite contained in this Cranberry granite. Magnetite is what the miners were after, and Cranberry had an excellent grade and a substantial amount of it. It has been determined that there is still a significant quantity of good ore still in the ground. In its 50 year life more than 2.5 million tons of waste rock and lean ore were removed from the hillside and mine at Cranberry and discarded, and another 1.5 million tons of good ore were sent to the furnaces at Cranberry and Johnson City. The national economic downturn and the lower costs of the massive ore deposits of the Mesabi Iron Range combined to shut the mine down in 1929. A magnet will stick to the wall in many places in the mine because of the high concentration of iron. Using a conventional compass here is completely out of the question. It is nearly impossible to see these rock faces in the spring and summer because of the vegetation.