Sterling Hill Mine
Deep inside the Sterling Hill Mine, a former zinc mine

A constant drip of water accompanies us as we follow our tour guide into the depths of a long-closed zinc mine in Ogdensburg, New Jersey. It is pouring outside, so the occasional drips on us as we walk down the mine tunnels aren’t a big deal. It’s a little muddy underfoot, since it’s so hard to keep a mine dry.

Ushering us into a dark tunnel, Dick hits the lights – the ultraviolet lights. Under their purplish glow, we see rainbows. Fiery red veins of calcite arc through vivid greenish-yellow willemite patches on the wall. Boulders on the floor glow in a crazy quilt of brilliant hues. Dick encourages us to pick up a small rock from the pile and hold it up to the light. I do, looking for flecks of yellow or pink that distinguish the rarer minerals. We’re all allowed to take one home.

zinc ore glowing
The brilliance of zinc ore under ultraviolet lights, underground

Rainbows in Rock

I grew up just east of Ogdensburg. One summer, Dad bought a gorgeous Cadillac convertible off one of his friends. When he opened the trunk of the new car, he found box lids filled with sparkling chunks of calcite studded with dark crystals. They’d come from the Franklin Mineral Museum, just up the road from the still-productive mine. That “pile of rocks” kicked off my lifelong interest in minerals, especially the weird ones found in the mountains I played in as a kid.

Calcite and willemite under UV
Calcite and willemite under shortwave UV. A specimen from my personal collection

Known to minerologists around the world as one of the top places to find fluorescent minerals – rocks that glow brightly under ultraviolet light – this narrow valley in the Appalachian Mountains of New Jersey has attracted attention from mineral collectors for several generations. Back when the mine still produced ore, miners discovered that the sparks created by their welding lit up the rocks like a christmas tree. In fact, they called the crystalline mix of willemite, zincite, and calcite “Christmas tree ore” and took rocks up to the surface in their lunch buckets to sell to collectors.

Rock Discovery Center monument
Under the care of Dick and Bob Hauck, the former mine is now a world-class earth science center

When Dick Hauck and his brother Bob bought the mine at a tax auction back in the 1980s, they knew they had a huge task on their hands, laying out plans for an educational complex focused on earth science. They wanted to tell both the story of the importance of mining and the uniqueness of this spot on earth. In this valley, more than 350 unique minerals have been identified – 89 of which glow under ultraviolet lamps – and more than 24 are found nowhere else on earth.

Interpreting the Past

Since it opened in 1990, I’ve watched the Sterling Hill Mining Museum grow from a couple of buildings and a handful of equipment to one of the most comprehensive collections of mining history east of the Mississippi River. More than 12,000 artifacts are on display in the Zobel Exhibit Hall in a building that was once the “change house” for miners to change in and out of their work clothes and get a shower after work. Clothing and boots hang from the ceiling; two rows of lockers give you a sense of how the building was once used.

Zobel Exhibit Hall
Looking for clues inside the Zobel Exhibit Hall

Our guided tour starts here, with Dick challenging everyone to browse the exhibits to find the answers to a set of questions about minerals and mining. A periodic table of the elements – complete with something for each element – fills one wall. The Oreck Mineral Gallery stretches across the back of the building, spotlighting colorful mineral specimens from around the world. Giant boulders of ore sit next to cases filled with antique mining lamps. Ever wonder what miners used for bathrooms underground while working? It’s here!

UV lit glass
Everyday items glowing under the UV lamps in the museum

In the Thomas S. Warren Museum of Fluoresence, set in a 1916 mill at the mine, we learn about the chemical properties of the minerals found in this mine with some hands-on lab experiments, and then move into the “ooh” and “aah” section, where an array of fluoresent minerals and objects from nature fill several galleries. Everyday items, like drinking glasses and postage stamps, dance under the glow of the ultraviolet lamps.

Into the Earth

Depending on the direction your tour group takes, you might enter the mine through the adit – the ground level entrance that the miners once used – or through a tunnel cut into the mine from the Warren Museum. Either way, you spend at least an hour underground.

Warren Museum
Inside the Warren Museum, you learn about fluorescence

In 1739, miners began digging out iron ore from the Sterling Hill Mine. The ore body here is unusually rich in many minerals, particularly zinc. Up through 1986, more than 11 million tons of ore came out of this mining complex. As we walked down the passageways of the mine, Dick stopped to test the ceiling and the wall with an iron bar, looking for a spot that would echo. “That’s the fault,” he said, when he found it. Don’t worry – rock bolts hold the ceilings in place.

Fault line
Dick points out the major fault that runs through the mine

One of the biggest problems with operating a mine is removing the water that seeps into the passageways. Not long after Dick and Bob bought the mine and started converting it into a museum, they had to shut off the pumps. The water table rose to its normal level, drowning most of the 35 miles of passageways. On a stop at the “grizzly” – a giant strainer that kept boulders from falling down to the next level and damaging the ore crusher – we could look down and see the water, one level below.

Throughout the passageways, dioramas present the mining equipment used underground, right in the locations where it was once used. Everything from the lamp room to the mancage (the miners’ elevator) and the ore skips (the elevator for the ore) is still in place. Dick explained how new ore tunnels were excavated using dynamite and heavy equipment, and how the ore was moved from the mine to waiting rail cars in the yard outside.

Rainbow Tunnel at Sterling Hill
Inside the Rainbow Tunnel

The delight of the tour, however, is the Rainbow Tunnel. Holding a brightly glowing rock in my hand, I’m reminded of my childhood mineral collection – what’s left of it packed up in boxes in a storage unit – and the joys of sharing something this weird with the kids in my life. Aunt Sandy will give them rocks for Christmas gifts this year!

Visiting Sterling Hill

The Sterling Hill Mining Museum is at 30 Plant St, Ogdensburg, NJ 07439. Hours vary by season, but the museum offers public tours daily April through October and on weekends November and December. Each tour takes at least two hours. It’s all level walking inside the mine. The air inside the mine is cool and damp, always around 56F, so you may want a sweater.

Sterling Hill Mining Museum
The museum is devoted to educating kids about earth science

For those who like to get their hands dirty (me! me!), the museum also offers periodic mineral collecting on the property, where you can find some of the rarest fluorescent minerals on earth from mine excavations brought to the surface many years ago. Some of these are night collecting, a lot of fun with a hand-held fluorescent lamp (bring your own). Some events are for museum members only. Check their schedule of events for details.

Just a few miles from Sterling Hill, the Franklin Mineral Museum offers not just a museum of fluoresent minerals but collecting minerals on their property during your visit. It’s where my childhood cache of “glowing stones” came from in the 1970s.