While I agree that it is pre columbian in style, I don't like the looks of the cartoonish look on the one side.
I haven't seen anything quite like it. I've been doing a lot of research and reading lately on the subject too, because I purchased a bunch of artifacts that I've been selling off on ebay recently.
It has a Cent/south Amer. look to it. When you said it was very heavy it reminded me of a bead I have from down there. Very heavy. I was told it was "ironstone". I don't know anymore about it. Gary