Pumice stone is a natural cleaning tool, says Dial-A-Maid Cleaning Service in Evanston, Il. 60201. It is actually hardened foam from volcanic lava. When we really do need an abrasive, pumice is gritty yet soft enough to be safe for certain purposes. Pumice is ground into a powder used for grinding and polishing as well as for cleaning. The grit in man made hand soap is usually pumice. Quarried blocks of pumice are also cut into bars that are used to remove stains and lime scale from toilet bowls, urinals, ceramic tile, and concrete. Pumice bars are helpful in scrubbing graffiti off brick and masonry and for scouring cooking grills and cast-iron cookware. Pumice stone has a hardness of 2. Generally, toilet is 5 or more, so it won't scratch, especially if you keep the stone wet while working with it. Wet it and then just rub it on the ring. the hard water calcium buildup should come right off. Then rinse and feel the area, if it's totally smooth, any ring that remains could just be a permanent stain. To speed up the removal of toilet bowl ring, you can apply acid bowl cleaner and scrub it in with the pumice bar. Be sure to wear rubber gloves when you do this.
Dial-A-Maid Cleaning Service in Evanston, Il. 60201, says you can use pumice on ceramic tile, masonry, cast iron, and other such hard, durable surfaces. Be careful, though. It will scratch enameled metal, plastics, fiberglass, cultured marble, plastic laminate like Formica, and softer materials.