The town of Marmora, originally named Marmora Iron Works, had seen mining activity as early as 1820.
In 1949 an aeromagnetic survey was conducted by the Ontario Dept. of Mines and the Canadian Geological Survey. The $40,000 survey revealed a magnetic anomaly that interested geologists at the Bethlehem Steel Corporation in New York.
In May, 1950 Bethlehem Steel purchased a 290 acre tract of property. The following year the company diamond drilled approximately 40 holes ranging from 460 to 1800 feet to further investigate the ore body.
In 1953 Bethlehem Steel began construction of the Marmoraton Mine. In order to gain access to the magnetite, the mine first had to blast away 120 feet of limestone. When initial blasting was complete, the open pit measured approximately 1700 feet by 1200 feet with a depth of 600 feet. In total over 73 million tonnes of rock has been removed from the open pit mine.
The Marmoraton Mine officially opened on May 11, 1955 with a ribbon cutting ceremony. The president of Bethlehem Steel, A.B. Homer cut a ribbon connecting the Powell Stackhouse ship to the ore dock in Picton. The ceremony was attended by federal, provincial and civic employees.
Marmoratan Mine was quite efficient. Once the crude ore was extracted, magnetic separators sorted the different minerals. The iron was concentrated into high density pellets that were easier to ship and more economical in making steel.
Each day 30 to 35 railway cars delivered iron ore pellets to Picton where they would be loaded onto boats and shipped to the company's blast furnaces in Lackawanna, New York. Annual product was in the range of over 520,000 tons of low-grade ore.
Two 250 horsepower water pumps removed over 20,000,000 gallons of water from the pit monthly.
The operation initially employed 270 local workers, a number that grew to approximately 300.
On January 3, 1978 Bethlehem Steel announced that due to poor business conditions the mine would close on March 31, 1978. The final shipment consisting of 23,833 tons of ore pellets was shipped on April 30th. Marmoratane Mine was then purchased by Armbro Holdings for potential use as a rock quarry.
Today the water pumps have fallen silent and the pit is estimated to be filled with 656 feet of water and officially classified as a lake.
Canada Talc Limited purchased the mill to process ore from the Madoc talc mine.
There is currently a proposal to build a unique hydro electric generating station on the abandoned site which would provide a source of stored electricity.