Physical Properties of Promethium and Thulium
Melting Point
1,042.00 °C
  
99+
1,545.00 °C
  
23
Boiling Point
3,000.00 °C
  
31
1,730.00 °C
  
99+
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Unknown
  
Silvery Gray
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Brinell Hardness
Not Available
  
Vickers Hardness
Not Available
  
Speed of Sound
Not Available
  
Not Available
  
Optical Properties
  
  
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available