Using a chisel, electric or manual, is really the only way to get the stone tiles up. I would use a small electric chisel, nothing too big. You have to be extra careful not to gouge your subfloor. Don't dig into your floor vertically. Work the chisel in a mostly horizontal position to keep from digging into your subfloor.
Michael Prachniak - Expert Tile and Stone Consultant and Writer, Owner - TileProductions.com
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