Uranium–lead radiometric dating involves using uranium-235 or uranium-238 to date a substances absolute age. This scheme has been refined to the point that the error margin in dates of rocks can be as low as less than two million years in two-and-a-half billion years.

Are Stable isotopes used for dating rocks?

Radioactive isotopes have known decay rates and half-lives, which are very useful for dating particular fluids or materials. Stable isotopes do not decay and are used to measure the ratios of the heavy isotope vs light isotope to reveal general conditions that would lead to this heavy/light isotope ratio.