Of all the different rocks I've seen on t-net thats the coolest. Looks more like glass. What state did it come from ?
It looks wet. I think it's naturally shaped from river tumbling. Looks like metamorphosed basalt ( because of the zeolite-like inclusions.) Not obsidian, not anthracite, not jet. IMO.
For some reason it reminds me of a sharks tooth , Re-shaped and coated.
not natural
Piece of jewelry made of glass or crystal. Unless you come up with more info (e.g., hardness) that's what it is.