cool i like that look.. ill try different ways on a different pieces of the foam to see if it comes out with something i like.. thanks for the tip.use the finest sand you can get, also dry soil ground down to powder and mixed with sand looks good. here is a close up of how mine came out-
the powdered soil helps it look more like stone and less like sand.
I just painted a thin coat of epoxy and dusted it with a heavy coat of soil and sand, then washed off the excess when the epoxy had cured.