Isotopes of rubidium
Rubidium has 36 isotopes, with naturally occurring rubidium being composed of just two isotopes; ⁸⁵Rb and the radioactive ⁸⁷Rb.
⁸⁷Rb has a half-life of 4.92×10¹⁰ years. It readily substitutes for potassium in minerals, and is therefore fairly... Wikipedia
Neutrons: 48
n: Neutron emission