For the most part, soapstone is a stain-resistant material. Occasionally, however, something may seep through the surface and leave a dark stain. Soapstone cannot be cleaned like other surfaces. It has a sensitive makeup that can be damaged if the correct materials are not used. Once you have completely removed the stain, you can prevent future stains by applying a coat of mineral oil to the soapstone surface.
Pour an all-purpose cleaner that has a neutral pH into a spray bottle. True 7 and Earth Choice are two examples of brands that sell cleaners with a neutral pH.
Spray the cleaner onto the stained area.
Dampen a soft cloth, and rub it in a circular motion over the stain. If the stain does not disappear, go on to step four.
Scrub the stain with 80-grit sandpaper until the discoloration disappears. This may take a while, but do not use anything rougher than 80-grit, or you will scratch the surface.
Pour mineral oil onto a clean cloth, and rub the cloth over the soapstone surface. Make sure the surface is covered with a thin layer of mineral oil, and let it seep into the surface. Repeat this process every eight weeks to prevent new stains from showing up.