Average atomic weight: 87.62(1) u
| Isotope | Fraction | Atomic weight/u |
| 84 | 0.0056(1) | 83.9134191(13) |
| 86 | 0.0986(1) | 85.9092606(12) |
| 87 | 0.0700(1) | 86.9088775(12) |
| 88 | 0.8258(1) | 87.9056125(12) |
Atomic weights and isotopic compositions were obtained from NIST Database 144
The Atomic Line List does not contain any data for this element
(Atomic Line List v3.00b5)
