Steep Rock Iron Range
As early as 1897 the presence of hematite boulders on the shores of Steep Rock Lake led geologists to suggest that beneath its waters lay a substantial iron ore body. It was not, however, until 1938 that a drill set up on the ice by Julian Cross of Port Arthur led to actual discovery of the ore. Steep Rock Iron Mines, Ltd., formed in 1939, undertook to reach the ore by diverting the Seine River and draining the lake. Late in 1944 Steep Rock began mining, and in 1960 the Caland Ore Company also came into production. By 1964 shipments by the two companies had totalled over 33 million tonnes.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.