At a Denver Gem and Mineral show I discovered obicular granite. These balls of dark stone form under very specific volcanic conditions. As far as I know they are found only in Peru, Australia, and Finland! The vendor who had a slab of this wonderful material sold me a large rock of it. I had the rock slabbed and used it in this piece.
In a moment of weakness, I traded the remaining slabs I had for some other, very interesting, rocks. If you have a slab or two of this material, I'd be please to make them into a table top for you.