Thanks Berlin for the reply. The reason why I ask is because I was on a hike and realized that the hiking trail was an old railroad right-of-way that fell into disuse and eventually the rails were removed. The town converted the line into a hiking path. I didn't know this until I spotted some curious black rocks and upon closer examination, it was coal. Anthracite to be specific.
I also found plenty of clinker. I walk this trail alot and come across some coal here and there, I just take it home and build up a nice collection of it. I've only found anthracite coal so far and no bit. But the abundance of clinker made me think that the trains may have burned some bit. This is Massachusetts so I figured that anthracite was more common due to geographical proximity to nepa. Until your post, I was under the impression that bit was the source coal for clinker and anthracite burned "cleaner". Thanks for clearing this up.