A high rise condo on the beach got flooded when a hurricane broke the windows.
Three months after the damage was cleaned up, dark, rust-colored spots started appearing on the granite and marble floor.
A visual inspection confirmed that the stone was showing iron oxidation (rusting). This is a common problem with certain stone types that are exposed to large quantities of water over a prolonged time period. Since these stones contained iron, it only took moisture for the oxidization to start.
In some less severe cases, there are some stain removal procedures that can be used, but in this case, the oxidation was so severe that total replacement was recommended.
Summary and Solution
In addition to a recommendation of replacement, since this condo was located in an area where another hurricane could cause damage again, it was suggested that an epoxy setting mortar be used for the new stone, which could help eliminate any future moisture that may sit in the stone.