Sulfur based metals treatment technologies show promise in being able to precipitate toxic and highly soluble metals into less soluble, less toxic metal sulfides for arsenic, lead, copper, zinc, cadmium, molybdenum, and uranium. Mobile hexavalent chromium is reduced to the insoluble chromium hydroxide, while cyanide forms less toxic thiocyanate. In all cases, treatment is pH dependent and can be an attractive remedial action compared to more conventional metals remediation methods such as excavation and pump and treat.