potassium-argon dating

a technique for determining the age of minerals based on the occurrence in natural potassium of a small fixed amount of radioisotope ⁴⁰K that decays to the stable argon isotope ⁴⁰Ar with a half-life of 1.28 × 10 ⁹years. Measurement of the ratio of these isotopes thus gives the age of the mineral Compare radiocarbon dating rubidium-strontium dating