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Monday, 29 October 2007

radioisotope. An unstable isotope of an element that decays or disinte­grates spontaneously, emitting radi­ation. Radioactive cobalt, cobalt-60, is one of the most common radioisotopes with a half-life of 5.3 years; radiation, beta and gamma. Cobalt-60 emits gamma rays which have about the same penetrating power as those of radium. Used for color treating Gemstones.