Radiometric dating
![Sm/Nd isochron plotted of samples [13] from the Great Dyke, Zimbabwe. The age is calculated from the slope of the isochron (line) and the original composition from the intercept of the isochron with the y-axis.](/uploads/202502/05/Sm_Nd_Great_Dyke_Isochron1904.png)
![A concordia diagram as used in uranium-lead dating, with data from the Pfunze Belt, Zimbabwe.[17] All the samples show loss of lead isotopes, but the intercept of the errorchron (straight line through the sample points) and the concordia (curve) shows the correct age of the rock.[12]](/uploads/202502/05/Pfunze_belt_concordia1904.png)
Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay. The use of radiometric dating was first published in 1907 by Bertram Boltwood and is now the principal source of information about the absolute age of rocks and other geological features, including the age of the Earth itself, and can be used to date a wide range of natural and man-made materials.