What conditions must a rock or mineral meet for a radiometric age to be reliable?

For a radiometric age to be reliable, a rock or mineral must satisfy several fundamental conditions to ensure the isotopic "clock" accurately reflects the time elapsed since its formation or a specific thermal event.12

The primary requirements are:

• Closed-system behavior: The rock or mineral must have remained a closed system, meaning there has been no addition or escape of parent or daughter atoms since the system formed. If daughter isotopes migrate out of the mineral due to heat or other processes, the calculated age will be inaccurate.1342
• Correction for initial isotopes: It must be possible to accurately account for any daughter atoms that were already present in the material at the time of its formation.15
• Known decay constant: The decay constant for the specific radioactive isotope being used must be precisely known.16
• Accurate measurement: The measurement of the daughter-to-parent ratio must be highly precise, as any uncertainty in this ratio directly impacts the reliability of the calculated age.17

Geochronologists often use internal cross-checks, such as analyzing multiple mineral types or using isochron methods, to validate these assumptions and ensure the integrity of the results.157