How to remove rust stains from flagstone porch?

Hi JoAnn, I did a bit of research on this topic and was surprised to learn how to get your flagstone clean. Clean the flagstone as best you can. Do this on a sunny day. Then put lemon juice (surprise) on the stains. Allow the juice to sit on the stains in direct sun for at least 5 minutes. Then sprinkle on some baking soda and scrub with a wire brush. Rinse with clean water. If stains are bad, you may need to repeat. Wishing you well.

You can also use powdered cleanser like Ajax or Barkeepers Friend, water and a wire brush, then rinse the stone, then sprinkle again while wet and let it stand for an hour, then rinse again. In nature, flagstone, limestone, fieldstone and many other rocks get rust. All it takes is for iron in the stone or soil to be exposed to air and washed through by water. That’s what gives the red and orange colors to so many stones, including marble. Best wishes ☺️

https://www.hunker.com/13423942/how-to-remove-rust-from-stone-or-flagstone

Thank you!