I can't seem to remove some old mortar-set tile. It's an old basketweave pattern that appears to have no grout at all...just square-edged tiles butted to one another. The amazing part...a sledge hammer doesn't break it! It just gives off sparks on impact! I have to remove it, but haven't a clue. I'm not looking to save it...just get it out. It's over a wood subfloor. Help!