Several weeks ago, our hot water heater developed a leak and flooded our kitchen floor. The floor is a white statuary marble, and it is starting to turn yellow. It is ten years old and we never had this problem until the flood. What’s happening

The problem you describe is very common with certain white marbles. Many marbles contain naturally occurring iron as part of their mineral make-up. When the stone is exposed to water for any length of time, its iron content begins to oxidize and turn to rust. The yellowing you see is the iron in the stone rusting. Under most circumstances, this oxidation will continue, and the floor will turn a steadily darker yellow and eventually a deep rich brown. The only solution is to replace the floor.