Rubidium-87

Rubidium-87 is a naturally occurring radioactive isotope of rubidium with a half-life of about 49 billion years. It decays to strontium-87 and serves as a parent isotope in geological dating.

Beta decay: Radioactive decay in which a nucleus emits an electron or positron, changing one proton-neutron balance. Rubidium-87 decays by beta-minus emission, becoming strontium-87.
Rubidium–strontium dating: A radiometric dating method that uses rubidium-87 decay and measured rubidium-to-strontium isotope ratios. It uses this isotope’s decay to determine ages of suitable rocks and minerals.
Isotope: One of several forms of an element whose atoms have the same proton number but different neutron numbers. Rubidium-87 is one isotope among rubidium’s naturally occurring forms.
Samarium–neodymium dating: A radiometric dating method based on the decay of samarium-147 to neodymium-143. It offers another long-lived isotope system for dating old rocks and tracing mantle processes.
Strontium-87: A stable isotope of strontium with 38 protons and 49 neutrons. It is the stable daughter product formed when rubidium-87 decays.
Isochron dating: A radiometric dating approach that estimates age from a linear relation among isotope ratios in co-genetic samples. Rubidium–strontium ages are commonly calculated with an isochron rather than assumed initial daughter abundance.
Rubidium: A soft, highly reactive alkali metal with atomic number 37. Rubidium-87 is a particular nuclear form of this element.
Uranium–lead dating: A radiometric dating method that uses uranium isotopes decaying through chains to stable lead isotopes. Its multiple decay chains provide a distinct dating clock and cross-check for ancient materials.
Radioactive decay: The spontaneous transformation of an unstable atomic nucleus into a different nucleus or energy state. The isotope’s long-term change is an instance of radioactive decay.
Geochronology: The science of determining the ages and timing of geological events. Rubidium-87 provides a long-lived clock for geological timescales.

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