|Isotope||Atomic mass (Da)||Isotopic abundance (amount fraction)|
Manganese is a monoisotopic element and its atomic weight is determined solely by its isotope 55Mn. The Commission last revised the standard atomic weight of manganese in 2013 based on the latest Atomic Mass Evaluation by IUPAP.
53Mn is radioactive with a half-life of 3.7(2) Ma, too short for survival of a detectable amount of primordial isotope. However, 53Mn has been identified on earth as a cosmic-ray product and as a constituent of cosmic dust amounting to approx. one disintegration per minute per gram of manganese in sediment cores corresponding to an abundance of 3x10-13, much too small to affect the standard atomic weight.
© IUPAC 2003