Iron out results

One other note about using Iron Out, it works better with warm or even hot water. Of course there can be an issue with using hot water and cold rocks, they can fracture. My trick for cleaning Arkansas Quartz in the summer is to use the water from a coiled hose on the west side of the house that sun has heated nicely. 

If cleaning rocks that have porous areas, I found it best to presoak the rocks in water for a while first for a few hours to saturate the porous area with water. Then add the Iron Out. This way the Iron Out saturated water will not penetrate into the porous areas as much. This can be a problem with something like Quartz Crystals on a sandstone base. After a few days out of the Iron Out solution, the porous areas will have the solution leach out and stain the base and even the crystals. I usually go from the Iron Out soak to a plain water soak for a day or two or more.