Now that's some interesting stuff with the thunderegg inlay. Very unique and very pretty. could you use a slice as the stricking surface? MAYBE.THE HARD AGATES AND SUCH DON'T REALLY WORK VERY GOOD FOR STRIKING SURFACES.YOU CAN'T HARDLY SCUFF THEM UP WITH SAND PAPER AND THEY SMOOTH OUT YOUR STRIKER SOMETHING FIERCE.I TEND TO STICK WITH SLATES AND METAMORPHIC ROCKS FOR STRIKING SURFACES.BUT THEY MAKE GREAT SOUND BOARDS AND INLAYS. C.JONES