143Nd

143Nd is a stable isotope of the lanthanide element neodymium (Nd), consisting of 60 protons and 83 neutrons. With a mass number of 143, it is one of the naturally occurring neodymium isotopes and makes up a measurable fraction of natural Nd. As a stable nuclide, 143Nd does not undergo radioactive decay.

Its geological significance comes from its connection to the long‑lived radionuclide 147Sm, which decays to 143Nd with a half‑life of about 106 billion years. This Sm–Nd decay system provides a means to date rocks and to study planetary differentiation and crust–mantle evolution. The evolving ratio of 143Nd to 144Nd in a rock reflects its Sm/Nd history and time since separation from a common reservoir.

In practice, Nd isotopic compositions are expressed as ratios (such as 143Nd/144Nd) and, for geochemical interpretation, as epsilonNd values relative to a reference reservoir (often CHUR, the chondritic uniform reservoir). Higher or lower epsilonNd values help distinguish mantle-derived versus crustal sources and track mantle differentiation through time. Nd isotopes, including 143Nd, are measured by mass spectrometry methods such as TIMS or MC-ICP-MS and are widely used in geology, geochemistry, and cosmochemistry to investigate the history of the Earth and other planetary materials.