Isotopes of calcium

41Ca has received much attention in stellar studies because it decays to 41K, a critical indicator of solar system anomalies.

Modern techniques using increasingly precise Thermal-Ionization (TIMS) and Collision-Cell Multi-Collector Inductively-coupled plasma mass spectrometry (CC-MC-ICP-MS) techniques, however, have been used for successful K–Ca age dating,[5][6] as well as determining K losses from the lower continental crust[7] and for source-tracing calcium contributions from various geologic reservoirs[8][9] similar to Rb-Sr.

Stable isotope variations of calcium (most typically 44Ca/40Ca or 44Ca/42Ca, denoted as 'δ44Ca' and 'δ44/42Ca' in delta notation) are also widely used across the natural sciences for a number of applications, ranging from early determination of osteoporosis[10] to quantifying volcanic eruption timescales.

[11] Other applications include: quantifying carbon sequestration efficiency in CO2 injection sites[12] and understanding ocean acidification,[13] exploring both ubiquitous and rare magmatic processes, such as formation of granites[14] and carbonatites,[15] tracing modern and ancient trophic webs including in dinosaurs,[16][17][18] assessing weaning practices in ancient humans,[19] and a plethora of other emerging applications.

[28][29] However, subsequent spectroscopic measurements of the nearby nuclides 56Ca, 58Ca, and 62Ti instead predict that it should lie on the island of inversion known to exist around 64Cr.