Physical Properties of Radium and Cobalt
Melting Point
1,495.00 °C
  
29
Boiling Point
1,737.00 °C
  
99+
2,870.00 °C
  
34
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Silvery White
  
Gray
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Mohs Hardness
Not Available
  
Brinell Hardness
Not Available
  
Vickers Hardness
Not Available
  
1,043.00 MPa
  
11
Speed of Sound
Not Available
  
4,720.00 m/s
  
14
Optical Properties
  
  
Reflectivity
Not Available
  
Allotropes
No
  
Yes
  
α Allotropes
Not Available
  
α-Cobalt
  
β Allotropes
Not Available
  
β-Cobalt
  
γ Allotropes
Not Available
  
Not Available