Nestled in a hillside in Hibernia, New Jersey, you’ll find the Hibernia mine (mindat.org page). In the 18th and 19th centuries, New Jersey was a top location for iron production. In the south there was bacteria-created “bog iron”, and in the north, in places like Hibernia, magnetite, magnetic iron ore, was torn from the bellies of mountains.

It took me a while to find the mine. The trail, starting at the trailhead at Green Pond Road & Lower Hibernia Road, forks in several places. One path leads to the graffitied ruins of a building, one leads to a pile of mine tailings, one leads to more ruins…

… and the top of the mountain, and one — the one you want — that heads toward the mine. Starting from the trailhead, I think it’s the second fork on the right; you walk up a hill and when you see what looks like the back of someone’s backyard, take the train on the left. When you get near the cave, you’ll feel the air get colder. There’s a wood platform on the left and on the right the final path to the mine.

As you get closer…

And closer to the mine entrance, you’ll notice the air coming from the mine is very chilly…

Freezing cold, in fact.

The mine is sealed off to protect it, and the bats who live there, from vandals and ne’er-do-wells. Though you cannot explore inside, what can be seen from the outside is visually impressive, and the cool air is a refreshing treat on a hot summer day.

Geologically speaking, you’ll find all kinds of interesting rocks in the park surrounding the mine: massive glacial erratics, purple & white “pudding stone”, pink granite, magnetite, biotite, milky quartz, and lots of banded, and some folded, gneiss. Migmatite, maybe?

In terms of hiking and discovery, throughout the park, you’ll find the collapsed entrances to mines, piles of tailing from mines, a cemetery for miners, stone ruins of building used to process ore, massive bear turds, and plenty of beautiful New Jersey nature.