How does radiometric dating determine the age of rocks?

Radiometric dating determines the age of rocks and minerals by measuring the ratio of radioactive isotopes (parent atoms) to their stable decay products (daughter atoms) within a sample.12

This process relies on the principle of radioactive decay, where unstable parent atoms transform into daughter atoms at a constant, known rate. Each radioactive isotope has a specific half-life—the time required for half of the parent atoms in a sample to decay. Because this rate is immutable and unaffected by external conditions like heat or pressure, scientists can use the measured parent-to-daughter ratio to calculate the time elapsed since the rock or mineral system formed.213

To ensure accuracy, geochronologists must assume the system has remained closed to the addition or escape of these atoms. Advanced techniques, such as the isochron method, are often used to account for initial daughter isotopes present at the time of formation and to provide internal consistency checks for the calculated age.24