The Arizona Department of Environmental Quality (ADEQ) surface water and soil test results of orange water and soil in the area surrounding the former Sheldon Mine (see sampling location map below) in Walker, Arizona, indicate the orange coloration is due to naturally-occurring iron. As iron is exposed to air, it forms iron oxide, which is orange or red in color. Based on the heavily mineralized geology in this former mining district, ADEQ tested the samples (surface water and soil) for metals (barium, cadmium, chromium, lead, mercury, selenium, silver, iron), arsenic, cyanide, and pH.
