The rarest of the stable lanthanides, and a portable X-ray source when irradiated.
- Atomic number
- 69
- Atomic mass
- 168.934 u
- Phase
- Solid
- Electron configuration
- [Xe] 4f¹³ 6s²
- Melting point
- 1,818 K · 1,544.9 °C
- Boiling point
- 2,223 K · 1,949.9 °C
- Density
- 9.32 g/cm³
- Electronegativity
- 1.25
- Period / Group
- 6 / —
- Discovery year
- 1879