32 APRIL 2025 WorldWide Drilling Resource® The Astonishing Story of Silver Islet Adapted from Information by Ontario Parks Beneath the icy waters of Lake Superior lies a mine shaft of Silver Islet in Ontario, Canada, renowned for being the world’s richest silver mine. Lake Superior’s shoreline residents and those familiar with the area recognize the lake’s perilous unpredictability. The lake can shift from calm to turbulent in a matter of minutes, unsettling even the most seasoned sailors. The creation of a nearly 1200-foot-deep hole in the ground under the lake could be incredibly difficult due to these conditions. Furthermore, to ensure operational capability, protecting the small island and constantly running pumps to remove accumulating water from the mine shaft would be essential. The mine, originally owned by the Montreal Mining Company, was deemed not worthwhile and sold it to Alexander H. Sibley, President of the Silver Islet Mining company, in the U.S., in 1870. This decision would ultimately prove costly, as the mine went on to become one of the world’s most successful silver mines. Considering the best approach to protect the mine from Lake Superior’s intense storms required evaluating all options. One engineer suggested building a wall around the island, which would have cost $2 million in 1870. An alternative proposal involved constructing smaller walls and pumps at a cost of $1 million. Despite these suggestions, both were extremely expensive and unable to guarantee the Islet would remain safe. The Silver Islet Mining company faced significant challenges in developing a plan to safeguard the islet, but the tide turned with the arrival of William B. Frue as lead engineer. Frue’s solution was to build a breakwall and install a pumping system to keep the mine shaft dry, estimating cost at $50,000 and requiring a workforce of 34 men. However, mining industry professionals were stunned by the plan’s ambitious scope, questioning whether it was possible to extract silver from beneath the lake on such a restricted budget with so few workers. Miners had to descend nearly 1300 feet into the ground every day through the mine shaft. A mine of this size is still considered substantial today and requires significant planning and advanced technology to guarantee the safety of the miners. As the shaft deepened, the timber supports eventually failed to support the weight of the overhanging mass of rock. Instead of loading the mine shaft with timber supports, Frue left a thick vein of silver running down the shaft to support the roof, a move that would eventually allow them to collect the silver and offset the cost of support. Communication was another challenge for the mining company, as well as for the miners and their families. With mail being the only means of communication, it was crucial for informing distant relatives of their safety. However, the community’s isolation, with no roads connecting it to the mainland, made mail delivery sporadic and inconvenient. This was particularly problematic for Frue, who relied heavily on regular communications with Sibley to manage the mine effectively. Before entering the U.S., mail crossing the border first had to go through the Pigeon River Border Crossing. When U.S. mail contractors refused to transport mail destined for Canada due to labor disputes, communication between Frue and Sibley became severely hindered. Fortunately, a deal was struck, and mail transportation was regulated. Upon the arrival of mail, the postmaster would raise the Union Jack flag to signal its arrival. After 13 years of extracting silver from beneath Lake Superior’s icy waters, operations at the remote mine ceased due to a delayed coal shipment, which caused the mine to flood and be reclaimed by the lake. Despite being closed for a century, the mine’s legacy lives on in Silver Islet, where some of the original miners’ homes remain. Today, the mine and the area surrounding Silver Islet continue to fascinate visitors who enjoy recreational activities at Sleeping Giant Provincial Park. Some historic buildings have been renovated, and the shore is now lined with summer camps in the shadow of the sleeping giant, protecting the sunken mine shaft. Silver Islet general store. Model of Silver Islet Mine on display at the Sleeping Giant Visitor Centre. Photo courtesy of Jeff Robinson. Mining office with Union Jack flag up. MIN
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