At this point the mineral begins to display measurable radioactive decay.
The U-Pb methods in green determine the ages of high temperature minerals (500-950°C), the 40AR/39AR methods in red have application in medium temperature minerals (150-550°C), and the (U-Th)/He methods cover the low temperature range (40-220°C).
However, they are very sensitive to being healed as mineral lattices adjust - even at quite low temperatures.
Consequently they give rather low "closure" temperatures (strictly called annealing temperatures).
Among the best-known techniques are radiocarbon dating, potassium-argon dating and uranium-lead dating.
By allowing the establishment of geological timescales, it provides a significant source of information about the ages of fossils and the deduced rates of evolutionary change.