Erbium (Er) has several isotopes, with the most stable and common isotopes being: 1. **Erbium-162 (Er-162)**: This is the most abundant stable isotope, comprising about 33.5% of natural erbium. 2. **Erbium-164 (Er-164)**: This is another stable isotope, making up about 1.6% of natural erbium.
