Not sure what's up there. Of course the mine is, I think they blocked it off/filled it in though according to articles I've read. There was a no trespassing sign on the chain blocking the path so I never ventured up there. Around 1848, Abraham Hewitt supposedly found some pig iron from the 1700's lying in the bushes, and was impressed with the quality.It's owned by Aeroflex, which is right near there on Limecrest Road.Supposedly that RR (Sussex Mine)only lasted 3 years, then turned into Sussex Railroad.The mines were very productive, the concentration of the ore was unique in composition, which led to a stronger type of steel. Andover put out a pamphlet, believe it was for a centennial, that talked about the mines. I believe I read about it at Sussex County Library in Wantage, NJ. Also, there is an Andover Historical Society that meets once a month. I'm sure they would have additional info.