Rock. The Roberts Mine was in operation until 1972, when the economic limit of the ore reserves was reached. When the mine closed, it was one of the deepest open pit mines in Canada at the time, with a vertical depth of 1100 feet. More than 18,000,000 tons of ore were mined during the life of this mine. Caland Ore Company Limited The Steep Rock directors decided that the east arm of Steep Rock Lake would be made available to other operators on a royalty basis. Inland Steel Company, a large American steel producer located in Chicago, became interested in the Steep Rock deposits. The ore body that was opened to being leased was the "C" ore body. Inland Steel first approached Steep Rock in January 1949 when two representatives went to Steep Rock to see the mining operations. Later both parties entered into negotiations for exploring the "C" ore body. Negotiations continued until December 8, 1949 when a lease was agreed upon. The terms of the lease included Royalties of 95 cents per ton, and the minimum tonnage was set at 3% of the proven reserves. The announcement was made January 12, 1950. Inland began an exploratory drilling program at the "C" ore body and in June 1951, it was apparent that there was no more than 27 million ton available. Inland went back to re-negotiate with Steep Rock about the terms of the lease. In October 1952, a new agreement was made. Inland created a wholly owned subsidiary to mine the ore body. The company was named Caland Ore Company Limited. Between the period of 1955-57, dams were constructed on Marmion Lake, the southeast arm of Steep Rock Lake and other locations around the area. Construction Aggregates Corporation was hired on to help with the dredging project at the "C" ore body. Two dredges were commissioned to work in the "C" ore body. The dredge "Clarence B. Randall"-named after the Chairman of the Board of Inland Steel- was launched on July 15, 1954. The other dredge "Joseph L. Block"- named after the President of Inland Steel- was launched on September 1, 1954. The two dredges were the largest at the time with the hull measuring 176 feet long by 50 feet wide with a depth of 14 feet. The dredging project was completed in 1960. A total of 160 million cubic yards of overburden (silt, water, rocks, etc.)