Beryllium-10

Beryllium-10 (10Be) is a radioisotope of beryllium. It is formed in the Earth's atmosphere mainly by cosmic ray spallation of nitrogen and oxygen. Beryllium-10 has a half-life of 1.39 × 106 years. It decays by beta decay to boron-10. It has a maximum energy of 556.2 keV. It decays through the reaction 10Be→10B + e−.
10Be and its daughter product have been used to study soil erosion, soil formation from regolith, the development of lateritic soils and the age of ice cores. It is also formed in nuclear explosions by a reaction of fast neutrons with 13C in the carbon dioxide in air.