There are a number of long-lived radioactive isotopes used in radiometric dating, and a variety of ways they are used to determine the ages of rocks, minerals, and organic materials.
Some of the isotopic parents, end-product daughters, and half-lives involved are listed in Table 1.
By the early 1960s, most of the major radiometric dating techniques now in use had been tested and their general limitations were known.
No technique, of course, is ever completely perfected and refinement continues to this day, but for more than two decades radiometric dating methods have been used to measure reliably the ages of rocks, the Earth, meteorites, and, since 1969, the Moon.
Radiometric dating is based on the decay of long-lived radioactive isotopes that occur naturally in rocks and minerals.