Isotope persisted down to the present because their rate of decay is so slow (e.g. uranium-238 and potassium-40). Post-primordial isotopes were created by cosmic ray bombardment as cosmogenic nuclides (e.g., tritium, carbon-14), or by the decay of a radioactive primordial isotope to a radioactive radiogenic nuclide daughter (e.g. uranium to radium). A few isotopes are naturally synthesized as nucleogenic nuclides, by some other natural nuclear reaction, such as when neutrons from natural nuclear fission are absorbed by another atom. As discussed above, only 80 elements have any stable isotopes, and 26 of these have only one stable isotope. Thus, about two-thirds
Archaeological science archaeological strata and artifacts. Some of the most important dating techniques include: Another important subdiscipline of archaeometry is the study of artifacts. Archaeometrists have used a variety of methods to analyze artifacts, either to determine more about their composition, or to determine their provenance. These techniques include: Lead, strontium and oxygen isotope analysis can also test human remains to estimate the diets and even the birthplaces of a study's subjects. Provenance analysis has the potential to determine the original source of the materials used, for example, to make a particular artifact. This can show how far the artifact has traveled