Found this at Point Bar. The black part looks like a layer on the rock. Although, there is some black mixed into the rock as well. Any ideas?




Thanks,

Hi Adrian! It looks to be a piece of slag to me. You may see alot of it by the railroad tracks. Just a guess but I hope this info helps you some.

Thanks Mrs. CP.

If that blackish-brown "bubbly" stuff is attached to rock, then it is probably NOT SLAG. I cannot see in the picture, but if it IS attached to rock, and inside the rock, then it is probably a "botryoidal form" of Chalcedony (micro-quartz). In that color it is commonly called JASPER.