Unusual Abstract Stone Sculpture / Marked Unkown Artist and Age.

Picked this up at GW last week. They had it on the front counter and it was only a few dollars. It's been sitting on the floor next to my desk. I really don't know what to make of it. It's not very large, about 11" tall by 8" wide. It's mounted to a cross section of rough sawn wood. I think it might be granite but I'm not much of a geologist. Interesting form and textures from rough to polished smooth depending on which way it's viewed. There are what look like two intertwined "S's" hidden on the very bottom edge. Not easily visible at first glance. Nothing on the bottom but some ugly green felt glued down with some really strong hard glue. I tried removing it to see if there was any info on the base but again nothing. I haven't had much luck trying to find the artist with just a couple letters to go on, but it's still pretty cool. -Mike-