Topaz and Blue John Physical Properties
Tenacity
Not Available
  
Not Available
  
Solubility
Not Available
  
Not Available
  
Durability
Not Available
  
Not Available
  
Specific Gravity
3.49-3.57
  
3.00-3.25
  
Fracture
Subconchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
  
Not Available
  
Cleavage
[001] Perfect
  
Not Available
  
Mohs Hardness
8
  
Not Available
  
Chemical Composition
Al2SiO4(F,OH)2
  
CaF 2Michael OâDonoghue , Gems, Sixth Edition (2006)
  
Topaz and Blue John Chemical Formula
While comparing Topaz and Blue John physical properties, the important data you should know is its chemical composition. Since chemical formula defines the molecular structure of the crystal, most of the physical properties like color, tenacity, solubility are governed by Topaz and Blue John chemical formula.
- Chemical formula of Topaz- Al2SiO4(F,OH)2
- Chemical formula of Blue John- CaF 2Michael OâDonoghue , Gems, Sixth Edition (2006)
Topaz and Blue John Specific Gravity
Another important criteria for qualitative analysis of gemstones is Topaz and Blue John Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Topaz and Blue John Optical Properties during the identification of gemstone. Specific gravity of Topaz is 3.00-3.25 whereas that of Blue John is 3.00-3.25.