Physical Properties of Promethium and Rhenium
Melting Point
1,042.00 °C
  
99+
Boiling Point
3,000.00 °C
  
31
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Unknown
  
Silvery Gray
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Mohs Hardness
Not Available
  
Brinell Hardness
Not Available
  
1,320.00 MPa
  
8
Vickers Hardness
Not Available
  
1,350.00 MPa
  
7
Speed of Sound
Not Available
  
4,700.00 m/s
  
15
Optical Properties
  
  
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available