The story of a forgotten America.

No. 7 Concentrating Mill

The No. 7 Concentrating Mill is a long abandoned mine and iron ore concentrating and separating plant in New York.


The first iron mining operation in the Adirondack Mountains region of New York began circa 1804 when Dr. Abijah Cheever, a local physician, accepted property as a debt payment. 3 It was soon discovered that the acreage contained valuable iron ore deposits, and a small mining operation for the iron was quickly put in place to meet local demands.

The completion of the Champlain Canal in 1823 linked Lake Champlain with the Hudson River and permitted the shipment of raw iron ore to various industrial centers in the Northeast and the Midwest. 2 3

The first pig iron blast furnace, fueled by charcoal, was built in Port Henry in 1827. In the early furnaces, iron was melted and agitated as a strong current of air was directed over it for the dissolved impurities to be oxidized. By 1865, there were eight such furnaces, 20 forges, three rolling mills, and two foundries. 3 The iron varied in quality, generally containing 60% iron and 30% to 40% phosphorus, 5 but were revered for their high percentage of magnetite. 2 By 1869, 160,000 tons of ore was being mined annually. 7

Most of the refined iron was consumed by the agriculture, construction, gas, oil, railroad, and shipbuilding industries.

Two railroads soon connected to the mining region. The Lake Champlain & Moriah Railroad opened in 1869, followed by the Delaware & Hudson in 1873. 7

Iron mining in New York peaked around 1870 and began to decline because of two significant developments. 3 More accessible mines were being developed around Lake Superior in Michigan, Minnesota, and Wisconsin. 2 With the completion of the Sault Saint Marie Canal in 1855, freighters could travel between Lake Superior and Lake Huron, simplifying the transport of ore to the Northeast and Midwest.

Additionally, the new Bessemer and open-hearth processes for manufacturing steel, fueled by coke, a byproduct of coal, could bypass the crude charcoal iron blast furnaces in the Adirondack Mountains. 3


In 1846, the Old Sanford Bed was conveyed to John Lee, George Sherman, and Eliphalet Hall. 6 The Hall share was then conveyed to S.H. and J.G. Witherbee, two New York industrialists, in 1849, at which point the Witherbee, Sherman & Company was formed. Over the ensuing decades, the mining company grew to be one of the most extensive operations of its type in the Adirondack region.

The onset of the Great Depression led Witherbee, Sherman & Co. to idle mines and ultimately led the company to sell its operations to the Republic Steel Corporation in 1938. 5

Demand for iron ore flourished in the early years of World War II due to the high demand for steel for the military. In March 1942, Republic Steel announced plans for the reopening of long-idled mines at Port Henry and Lyon Mountain by July 1943. 11 It would also involve the construction of a $5 million community with 1,000 homes and a school for 800 students. The company was also expending $6 million to develop a new mine 11 and what became the No. 7 concentrating mill. 6

At the new concentrating mill, iron ore was fed by a conveyor belt to high-intensity wet magnetic separators. 4 The metal was then passed over several screens to separate the rock into different sizes. While the tailings were discharged to a waste tailings area, other types of rock were fed into concrete silos and crushed for use as a roadway base and for mixing into the asphalt. Republic Steel sent the concentrated and sintered iron by rail to its integrated steel mills in Buffalo, New York, Cleveland, Ohio, Youngstown, Ohio, and Warren, Ohio. 6

By the late 1950s, the mining operations under Republic Steel deteriorated because of high costs. With shafts that were 3,000 feet below the ground and veins that extended for miles, it could take up to four hours for workers in a typical shift to reach iron ore veins. 1 5 Foreign imports of steel also began cutting into Republic Steel’s profits. 10 The mines closed periodically, and in 1960, the company shut down its operations for several months while it reorganized. 6 When it reopened, the workforce of 800 was cut in half.

Republic Steel began studying the feasibility of constructing a new shaft that would connect to millions of tons of high-grade iron ore under Lake Champlain, but it was determined to be far too expensive to build at the time. 10

The company idled its Adirondack Mountain facilities in July 1971 for a summer “vacation” period that was mandated by the local union, but Republic Steel decided to mothball all operations in September temporarily. 8 The company opted to close the mines and mills in 1980 permanently. 9

In the 1980s and 1990s, Rhone Poulenc inquired about the tailings, hoping to mine the discarded waste for rare earth minerals.

The deep underground mines may be reused as part of a hydroelectric storage facility. 1 In the hydroelectric operation, water would be pumped from one level of the shaft to another. Electricity generated at other hydroelectric plants at night time, when demand is typically low, would be transmitted to the Witherbee facility. The power arriving at the lower level of the storage facility would pump water into the higher level. The next morning, when electricity rates would be higher, the water would be released to flow back into the lower level through a turbine that would generate electricity to be sent back into the grid.



  1. Thompson, Maury. “Mining history may leave Moriah awash in new project.” Post-Star [Glen Falls], 1 Dec. 2005.
  2. The Iron Mine, Port Henry, New York. Smithsonian American Art Museum, Dec. 2011, article.
  3. History of the Iron Industry of Essex County, New York, by Frank S. Witherbee, 1906.
  4. “New York’s Iron Capital.” Moriah and Port Henry in the Adirondacks, by Jacqueline Ann Viestenz and Frank Edgerton Martin, Arcadia, 2013, p. 19.
  5. “Introduction.” Moriah and Port Henry in the Adirondacks, by Jacqueline Ann Viestenz and Frank Edgerton Martin, Arcadia, 2013, p. 9.
  6. Garofalini, Linda M. The Historic and Architectural Resources of the Town of Moriah, Essex County, NY. National Park Service, Jan. 1995.
  7. “Addendum to Patrick F. Farrell Collection” Adirondack Experience. Entry.
  8. “Republic Steel Corp. Closing Mines at Port Henry.” Post-Star [Glens Falls], 9 Sept. 1971, p. 1.
  9. Martin, Mike. “Moriah: Reputation to shake, pride to restore.” Post-Star [Glens Falls], 17 Oct. 1989, p. B3.
  10. Metivier, Don A. “‘Merry Christmas’ for Miners Despite Steel Firm’s Shutdown.” Post-Star [Glens Falls], 24 Dec 1971, p. 14.
  11. “Boom in Mining to Build Village.” Ithaca Journal, 2 Mar. 1942, p. 10.


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I went here recently its going to be torn down soon the property is gated off with barbed wire by the main entrances with lots of posted and no trespassing signs. so i went in the back way that’s by of a pond (mabe lake) that had a small dam and where the trees were cleared for powerlindes we hiked in the wools along what looked like a an old tral and ended up crossing a river then finding the pump house and the rest of the mill buildings the only reason the property manager found us was because he found are car. the 2 main building are locked up tight but the lower ones are not.

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