26Mg

26Mg is a stable isotope of magnesium with mass number 26. It is one of the three stable isotopes of magnesium, the others being 24Mg and 25Mg. The nucleus contains 12 protons and 14 neutrons. As an even-even nucleus, 26Mg has nuclear spin I = 0 and no intrinsic magnetic moment.

Natural magnesium consists of about 11% 26Mg, with the remainder mainly 24Mg and 25Mg. The isotope is non-radioactive and found in minerals wherever magnesium occurs, including geological samples, meteorites, and biological materials.

In stellar environments, 26Mg is produced primarily by neutron capture on 25Mg (25Mg(n,γ)26Mg) and, to a lesser extent, from successive captures on lighter Mg isotopes. It is used in studies of stellar nucleosynthesis and galactic chemical evolution, as its isotopic ratio traces neutron-capture processes.

26Al decays to 26Mg with a half-life of about 0.7 million years. The in-situ decay of 26Al shortly after the formation of early solar system materials produces excess 26Mg, a key chronometer in cosmochemistry for dating refractory inclusions and early solar system events.

Analytical techniques such as thermal ionization mass spectrometry (TIMS) and multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) measure 26Mg/24Mg and 26Mg/25Mg ratios, enabling studies of isotopic fractionation, planetary differentiation, and solar system formation.