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Before the United States was a country, New Jersey was mine country.
State officials are aware of about 2,700 sites where mining or prospecting took place in the Garden State. The state Department of Environmental Protection lists 588 abandoned mines in its database, covering coveted minerals from copper to zinc. Some of the mines are thought to date to the 1600s.
For the most part, miners in the Garden State were after iron. More than 85% of the state’s abandoned mines excavated iron-bearing magnetite ore from a wide band of hard rock formations known as the Highlands Region.
Story continues below map of abandoned mines in New Jersey.
The Mount Pleasant Mine is under Route 80
All eyes recently have been on one mine in particular: Mount Pleasant Mine. Thought to be directly under the Avalon Wharton housing complex and Interstate 80 near the sinkholes, the mine was worked from 1786 until 1896, U.S. Geological Survey records show.
Upon closure, Mount Pleasant Mine dipped below sea level from a ground elevation of roughly 700 feet and stretched 2,300 feet, with workings leading from the primary shaft to the northeast and southwest, USGS records show. The magnetite deposit it tapped was worked by several other mines in the Wharton area, including the Hurd Mine in the center of Wharton, the massive Richard Mine on Mount Hope and the Orchard Mine to the southwest near Washington Forge Pond.
New Jersey mine collapses and sinkholes
The latter suffered a pump shaft collapse in August 2000 after the pond overflowed during torrential rainfall earlier that month, the Daily Record reported at the time. The resulting sinkhole, about 15 feet wide and 30 feet deep, opened behind the local American Legion hall, prompting police to secure the area.
Cement was later used to fill the sinkhole and reinforce the hall’s destabilized foundation. Officials later suggested that an unusually dry summer in 2000 may have weakened the mine’s shaft-supporting timbers, making them brittle and susceptible to failure when heavy rains arrived, the Daily Record reported in July 2002.
Another mine that has suffered collapses in the past is one of New Jersey’s more interesting: North Arlington’s Schuyler Mine. A copper mine cut in sandstone, New Jersey Geological Survey records show, it has shafts in the area around Avon Place, Exton Avenue and Schuyler Avenue. Dating from about 1712 to 1713, its first ore hauls were sent directly to Europe, as the colonists were not allowed to refine any copper they mined.
Schuyler Mine was the rare profitable copper mine in the colonies, former state resident Benjamin Franklin said in a 1750 letter, but flooding posed such a problem that the family owning it was forced to spend a fortune to have a steam engine delivered from England to pump out its shafts and tunnels.
Flooding nevertheless remained a problem for the Schuylers and many subsequent owners, including the New York and New Jersey Mining Company. According to state records, that company took over the site in 1892 and damaged the mine’s pillars, causing multiple cave-ins, before abandoning the site.
The Schuyler mine was almost revived at the turn of the 20th century by the newly formed Arlington Copper Company. It planned to use electrolytic extraction to purify the copper ore and invested heavily in the infrastructure, New Jersey Geological Survey records show. However, that also failed within a few years.
What was harvested in New Jersey’s mines?
Some of the state’s other more interesting mines include the ones with workings still evident on Sparta Mountain. Those were tapped by Thomas Edison in the 1890s and have been preserved as parkland. There is also the Hurdtown Apatite Mine, which harvested blue, gemstone-like crystals from below what is now a ballfield in a suburban development along Lake Hopatcong.
There is also the Scrub Oaks Mine in Mine Hill. An oddity among the belt of magnetite mines around Dover, Scrub Oaks also held iron-heavy hematite and radioactive rare-earth minerals studied by federal geologists in the 1950s. There are also the Peter’s and Cannon mines in northern Ringwood, where Ford Motor Co. officials had tons of industrial waste and paint sludge dumped a couple of decades later, to the detriment of a residential neighborhood many members of the Ramapough Lenape Nation call home.
Sterling Hill mine glows in the dark
Perhaps New Jersey’s most famous mine is nonetheless the New Jersey Zinc Company’s former operation on Sterling Hill in Ogdensburg, where folds of marble encase zinc deposits and fluorescent minerals that glow in the dark.
Story continues below photo gallery.
The company operated a twin zinc mine in nearby Franklin that tapped into the same 1.3 billion-year-old geologic formation that extends from Sparta to Warwick, New York. Between the two mines, more than 365 mineral species have been documented to date, ranking the area among the most mineralogically complex locations in the world.
During their lifespans as active zinc mines, the Sterling Mine in Ogdensburg yielded over 11 million tons of zinc ore and the Franklin mine produced twice that amount, says the Sterling Hill Mining Museum website.
The Sterling Mine, the last operating mine in New Jersey, suspended large-scale commercial mining operations in 1986. Since then, it has become a popular tourist attraction and educational center that takes visitors into damp, marble-lined tunnels to see the glowing rocks within.
