Early methods relied on uranium and thorium minerals, but potassium—argon, rubidium—strontium, samarium—neodymium, and carbon—carbon are now of considerable importance. Uranium decays to lead with a half-life of 4. It is important that the radioactive isotope be contained within the sample being dated. Carbon is contained within plant material, but potassium, argon, and uranium are contained satisfactorily only within crystals. Igneous rocks are the most suitable for dating.
Radiometric dating - Wikipedia
Radiometric dating , radioactive dating or radioisotope dating is a technique used to date materials such as rocks or carbon , in which trace radioactive impurities were selectively incorporated when they were 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. Together with stratigraphic principles , radiometric dating methods are used in geochronology to establish the geologic time scale. 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. Radiometric dating is also used to date archaeological materials, including ancient artifacts. Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied.
What is Radioactive Dating? - Definition & Facts
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Many rocks and organisms contain radioactive isotopes, such as U and C These radioactive isotopes are unstable, decaying over time at a predictable rate. As the isotopes decay, they give off particles from their nucleus and become a different isotope.