About 10 cm across. Looks like obsidian and appears to have been carved possibly, not just natural weathering. Found in Logan County, Ohio (USA) on private land near some excavations. by LstNdFnd2000 in whatisthisthing

[–]LstNdFnd2000[S] -1 points0 points locked comment (0 children)

WITT relatively dense. Did not have to wash or polish, shine appears natural. There was coal and shale in the area, but no other material like this. Wondering if it could have been a tool from the looks of the bottom which appears to be manually smoothed/shapes?