 An overview of the gamma sources used for radiography can be seen at Radiographic equipment, and it is reasonable to consider this to be a good overview of small to moderate gamma sources.The cleanup operation for the Goiânia accident was difficult both because the source containment had been opened, and the radioactive material was water-soluble.In 1983, a different incident in Mexico wherein cobalt-60 was spilled in an otherwise similar exposure led to a very different pattern of contamination, since the cobalt in such a source is normally in the form of cobalt metal alloyed with some nickel to improve the mechanical properties of the radioactive metal.