RADIOGENIC

A 'radiogenic' nuclide is one that is produced by a process of radioactive decay.
Lead is perhaps the best example of a radiogenic substance, as it is produced from the radioactive decay of uranium and thorium. Specifically, Pb-206 is formed from U-238, Pb-207 from U-235, and Pb-208 from Th-232. Other substances considered radiogenic are argon-40, formed from radioactive potassium, and nitrogen-14, which is formed by the decay of carbon-14. U-238, U-235, and Th-232 themselves are likely to be radiogenic as well, being formed from the decay of those nuclei of the elements heavier than uranium which do not undergo spontaneous fission, just after they were formed in stellar supernovae.
Other important examples of radiogenic elements are radon and helium, both of which form during the decay of heavier elements in bedrock. The global supply of helium is radiogenic.