Physical Properties of Promethium and Terbium
Melting Point
1,042.00 °C
  
99+
1,356.00 °C
  
33
Boiling Point
3,000.00 °C
  
31
3,123.00 °C
  
29
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Unknown
  
Silvery White
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Brinell Hardness
Not Available
  
Vickers Hardness
Not Available
  
Speed of Sound
Not Available
  
2,620.00 m/s
  
35
Optical Properties
  
  
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available