This is when the original nuclide splits to form two equal sibling nuclides. The other nuclide from the branching undergoes electron capture to form Ar-40. Such is the basis for this dating method. Now that the procedure has been discussed, let us look at the practical uses for this type of dating method. First suggested in 1940 by M.I.T. physicist Robley D. Evans, this method of dating has come a long way in the sixty years since its proposal.
Potassium is the seventh most abundant element in the crust of the earth.
Thus, it is found in almost all rock-forming minerals. Also allowing a wide range of use is the ease at which K-40 decays. Another benefit of this method is the fact that Argon is an inert gas, which means it can be easily detected and measured in nearly all minerals. On the other hand, there are several assumptions that have to be made before the Potassium-Argon method will work completely. The decay of Potassium-40 occurs at a constant rate, regardless of its chemical or physical environment.