Mysterious Stains on Marble Patio Pavers

Q. Help! I have mysterious stains on my new marble patio pavers. Our stone was set in sand over concrete less than two weeks ago. We noticed red-brown stains after it rained. I’m frustrated because I can remove the discoloration when I clean it with various products - Dawn, hydrogen peroxide, Iron Out, mold and mildew remover, bleach water, etc., but the stain keeps coming back within a few hours.

A. The staining you are seeing is likely the result of iron oxidation, but without seeing it in person, no professional can diagnose the problem with absolute certainty. Many natural stones contain iron that, when exposed to moisture, will oxidize. In other words, the iron in the stone will rust. Florida is notorious for humidity and afternoon thunderstorms. Unfortunately, with natural stone, it is impossible to tell which tiles will contain more iron than others prior to installation. Your installation may need to be replaced by a type of stone more appropriate for the environment, unless the discoloration has some cause other than iron oxidation. Before you have your stone replaced, have a stone restoration PRO come take a look.