The New Jersey Highlands are festooned with abandoned iron mines, many of which are still visible. Some mines, like the Hibernia Bat Mine have large openings you can walk up to. Some are filled with water and tailings. Others are hidden behind fences and thickets of trees, weeds and vines.
Canfield’s Phosphate Mine is an old iron mine located in Mine Hill Township, New Jersey, along Canfield Ave, nestled behind a fence and hidden by trees. Little remains other than a shaft that is visible through the chain link fence. Visitors cannot access it, but it is cool to see.
See the Mindat page for more information. Canfield’s Phosphate Mine, today, is best known for pink fluorescent Apatite found in old tailings from the mine. Pink fluorescent Apatite is found throughout the Highlands.
If you want to visit the inside of an actual mine in New Jersey, I highly recommend The Sterling Hill Mining Museum in Ogdensburg, NJ. Sterling Hill was a zinc mine (not iron) that is best known for fluorescent minerals like willemite and sphalerite.