|Also called: radioactive dating any method of dating material based on the decay of its constituent radioactive atoms, such as potassium-argon dating or rubidium-strontium dating|
|an extraordinary or unusual thing, person, or event; an exceptional example or instance.|
|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
|radiometric dating (rā'dē-ō-mět'rĭk) Pronunciation Key
A method for determining the age of an object based on the concentration of a particular radioactive isotope contained within it. For inorganic materials, such as rocks containing the radioactive isotope rubidium, the amount of the isotope in the object is compared to the amount of the isotope's decay products (in this case strontium). The object's approximate age can then be figured out using the known rate of decay of the isotope. For organic materials, the comparison is between the current ratio of a radioactive isotope to a stable isotope of the same element and the known ratio of the two isotopes in living organisms. Radiocarbon dating is one such type of radiometric dating.