It all depends on the environment and the treatment. These old poles that they called Black Diamonds were hard as a rock. I climbed one with a date nail in it from 1928. The date nail was put in to signify what year the pole was set. Let me go dig it up and show you hang on....
I climbed that when I was a 2nd step apprentice so that would have been 2006-2007. They can last a Loooooong time. Lol
Are Black Diamonds made out of a pine tree?
I’m not sure what exactly species of pine but yes they are. The treatment they use on them is what makes them so hard and last so long. I imagine it’s some pretty toxic stuff. Lol
I think that I may have seen what you are talking about at a sub-station where there appeared to be some burnt telephone poles. Do you think that it might be some sort of chemical treatment?