We decided to keep the marble fireplace which has more of a retro look and is not original to the house. It involved cleaning it thoroughly, light sanding where soot had built up heavily and using a poultice powder to pull out a nasty rust stain from a flower pot on the top. This stain was really tough and makes me want to rethink ever getting a marble fireplace. It took about 2 weeks of adding poultice, leaving it covered with plastic wrap, then removing the dried poultice paste that sucked some of the stain out of the stone. We also replaced the black slate that was worn with new pieces.