Union County's Watchung Reservation is well known among New Jersey adventurers as home of the Deserted Village, but it holds other surprises that aren't as evident, even when you practically trip over them.
If you take a right turn after the trail head near the Trailside Nature and Science Center, you'll eventually come upon a bunch of ravines. They look entirely natural, but one isn't quite what it appears to be. In fact, it's the last remnants of a very old copper mine. You'll know you found it when you come upon the interpretive marker (if it's still there) or a four-by-four post with a pink stripe around it (if it's not). Oh, and you might notice some rocks with a slight greenish tinge on them, that being the traces of very low-quality copper.
The area isn't as well known for mining today as other parts of the state are, but its history goes far back. Park literature theorizes that the First Watchung Mountain ridge may have been scouted for copper by the Lenape as far back as 500 years ago. Another source noted that the area was first settled by English miners in the 1600s. Either there was really something there, or speculators were highly motivated to take a chance at making a big strike in the New World. I'm betting on the latter more than the former.
The more interesting story, in my book, is what may have happened there during the Revolutionary War. It's believed that Hessian prisoners of war were held in what's now Mountainside, and brought to the mine site to dig for copper for military use. The famed Schuyler Mine in the North Arlington area was closed at the time, and perhaps the Continentals thought they could hit pay dirt farther south along the ridge. In any case, the Hessians only got about fifteen feet in before digging was halted; the ore they found was deemed not to be worth the time to extract, transport and process. If there were any other mining attempts within the current reservation borders, they're not evident today.
As I was researching the Reservation's mining history, I found the usual apocryphal mine stories: deep underground rooms haunted by a kid who got lost and trapped by a cave-in, you name it. All that tends to go out the window when you see the actual location. If there's someone stuck in there, he's been there for an awfully long time.
*Apologies to Jimmy Cagney for mangling his quote from Public Enemy.