A rich vein of pure silver was discovered on the island in 1868 by the Montreal Mining Company. At that time, the island was approximately [50 m²] in size and only 2.5 metres above the waters of Lake Superior. In 1870, the site was developed by Alexander H. Sibley's Silver Islet Mining Company which built wooden breakwaters around the island to hold back the lake's waves and increased the island's area substantially with crushed rock. The islet was expanded to over 10 times its original size and a small mining town was built up on the shore nearby.
After most of the purest ore from the original site had been removed, a second vein was discovered in 1878. By 1883, most of the highest quality silver had been extracted and the price of silver had declined. The final straw came when a shipment of coal did not arrive before the end of the shipping season. The pumps holding back the waters of the lake failed and the mine shafts which had reached a depth of 384 metres were flooded in 1884.
Over the 16 years that the mine was in operation, 3.25 million (1880's) dollars worth of silver was extracted.
The houses originally built to house miners are now used as private summer cottages The general store has been restored, and serves light meals in its tea-room, in addition to selling a variety of knicknacks and basic foodstuffs.
Sleeping Giant Provincial Park has an excellent exhibit in its visitor centre, detailing the structure and history of the mine.
There is speculation that much silver remains to be recovered at this location, but attempts to reopen the mine in 1919 and the 1970s (reprocessing mine tailings) were not successful.
The Silver Islet Mine was also where "Vanners" were first used commercially to extract metal from low-grade ore. Known as the "Frue Vanner" as it was named for W.B.Frue, Superintendent of the Silver Islet Mine, who developed the system, it was first installed at the "Stamp Mill" beside "Frue's Brook" on the mainland. Modern versions of the Frue Vanner are still in use today. To learn more about Silver Islet Visit www. silverisletcampers.ca
Silver Islet, specifically the missing coal shipment in 1883, is the subject of the Tanglefoot song "One More Night". Silver Islet is featured as the hometown of Sarah, a waitress, in Jane Urquhart's novel The Underpainter.