Marble fireplace surrounds are attractive and often easy to simply wipe down with a damp cloth if they become dusty or sooty. But to protect this type of natural stone from being burnt or stained, it should be adequately covered. The correct type of cover for marble or granite is a masonry sealer, which will continue to cover and protect your surround if you reapply it each year.
Wash the surround with mild, soapy water and a rag and remove any stains. Rinse the marble when it is clean and let it dry one to two days.
Apply a topical natural stone and masonry sealer to a clean, soft cloth. Rub the sealer over the marble, using the cloth. Coat the marble evenly and thoroughly with the sealer.
Blot any excess sealer from the surface of the marble, using a clean cloth. Wait one to two hours and buff over all of the marble with a third, unused cloth. Do not use the fireplace for 24 hours to ensure that the sealer has completely dried within the marble.
Cover the marble around your fireplace with a new layer of sealer once a year.