204Pb

204Pb is a stable isotope of the element lead (Z = 82) with a mass number of 204. It consists of 82 protons and 122 neutrons and is one of the four stable isotopes of lead, with a natural abundance of about 1.4%.

In nuclear terms, 204Pb is an even-even nucleus, and its ground-state spin is 0+. No radioactive decay has been observed for 204Pb, and its half-life is effectively infinite for practical timescales, making it treated as non-radiogenic in geochemical studies.

Occurrence and applications: 204Pb occurs naturally in lead and represents a small but measurable portion of natural lead. Because it is not the product of radioactive decay within the uranium–thorium system, 204Pb serves as a reference isotope in lead isotope geochemistry. In Pb-Pb dating and isochron methods, 204Pb is used to infer the initial lead composition of materials by comparing radiogenic isotopes (206Pb, 207Pb, 208Pb) to 204Pb. This baseline allows scientists to reconstruct ages and growth histories of rocks and minerals. Lightly, 204Pb data are also used in instrumental calibration and mass-bractionation corrections in isotopic measurements.

Overall, 204Pb is treated as a stable, non-radiogenic component of natural lead, playing a crucial role in isotopic dating and geochemical tracing of lead in geological materials.