The Glowing Underworld: Going Underground in Ogdensburg, NJ

When you think of New Jersey, you might think of the Shore, the suburbs, or the Turnpike. You probably don’t think of world-class mineral deposits.

But hidden beneath the small borough of Ogdensburg in Sussex County is a geological wonder that rivals any in the world. This is the Sterling Hill Mine.

The Record Holder: Together with the nearby Franklin Mine, this district contains over 357 types of minerals—roughly 10% of all minerals known to science.
The Uniqueness: 35 of these minerals have never been found anywhere else on Earth.
The Glow: An astounding 91 of these minerals fluoresce, meaning they glow in vibrant neon colors under ultraviolet light.

A Billion Years in the Making

The geology here is ancient. The ore bodies lie within the “Franklin Marble,” formed approximately 1.15 billion years ago.

While Dutch settlers may have poked around the area in the 1600s, the first documented mining began in the 1730s on the “Copper Mine Tract.” (Ironically, the early miners were fooled; the bright green minerals they saw weren’t copper, but rather distinct local minerals).

The Founding Fathers Connection: In 1769, the land was acquired by William Alexander (Lord Stirling), a Major General in the Continental Army. Though he primarily mined iron, the mine bears his name to this day.

The Zinc Capital of the World

In the 19th century, scientists realized the true value of the site: Zinc. The ore here is rich in three unique minerals:

Franklinite (Iron, Zinc, Manganese)
Zincite (Zinc Oxide)
Willemite (Zinc Silicate)

In 1897, the various small mines were consolidated under the New Jersey Zinc Company. By 1912, they abandoned the open pits and went underground.

The Depth: At its peak, the mine shafts plunged 2,675 feet below the surface.
The Scale: There are 35 miles of tunnels winding through the rock beneath Ogdensburg.

The Edison Connection: Even Thomas Edison got involved. In the 1890s, the Wizard of Menlo Park invested millions in a nearby iron mine and offered technology advice to the New Jersey Zinc Company. Though his own mining venture nearly bankrupted him, his innovations in rock crushing were adopted by the industry.

The Last Mine Standing

The Sterling Hill Mine operated continuously for nearly 138 years. However, a tax dispute with the town and falling zinc prices forced it to close in 1986. It was the last operating underground mine in New Jersey.

Instead of flooding the tunnels and walking away, brothers Richard and Robert Hauck bought the site at auction in 1989 for $750,000. They transformed the industrial site into a museum, which opened to the public in 1990.

Going Underground

Today, you can walk into the side of the mountain and experience the life of a miner.

The Tour: Visitors walk roughly 1,300 feet into the mine through the main adit. The temperature remains a constant 56°F year-round.
The Rainbow Tunnel: The highlight of the tour is the “Rainbow Tunnel,” where shortwave ultraviolet lights are turned on, causing the walls to explode in glowing reds (calcite) and greens (willemite).

Above Ground Treasures: The museum complex is massive.

The Change House: This building, where miners once showered and changed, now houses the Oreck Mineral Gallery, displaying rare specimens and mining artifacts.
The Warren Museum of Fluorescence: Located in the ruins of the 1916 mill, this exhibit showcases glowing minerals from around the world.
The Observatory: In 2005, an astronomical observatory was added to the site, taking advantage of the dark skies of Sussex County.

If You Visit

Location: 30 Plant Street, Ogdensburg, NJ 07439.
Tours: Guided tours generally run on weekends at 1:00 PM, but check the schedule as it changes seasonally.
What to Wear: Bring a light jacket! Even in the summer, the mine is a chilly 56 degrees.

For More Information

Sterling Hill Mining Museum (www.sterlinghillminingmuseum.org)