Cadmium is a metallic element that occurs naturally in the earth's crust, especially in zinc-, lead-, and copper-bearing ores (Forstner and Whittmann, 1981). Pure cadmium is a soft silver-white metal, but is rarely found naturally in its pure form. It is commonly combined with other elements, such as oxygen (cadmium oxide) and sulfur (cadmium sulfate).
Information Circular 9
Digital Object Identifier (DOI)
Davidson, Bart and Fisher, R. Stephen, "Groundwater Quality in Kentucky: Cadmium" (2005). Kentucky Geological Survey Information Circular. 7.