What kind of rock(?) is this? Found in a small creek in southern Ohio. It has what looks like a pale green glass glaze surrounding it that doesn’t show up very well in photos. Top surface shows heavy abrasion and bottom surface has some small bubbles in the glaze and below surface in the rock. It’s not any heavier than local rocks of its size and I detect no metal content. My first uneducated thought is possibly volcanic in nature but that isn’t likely in Southern Ohio. Any ideas?
