Topaz and Alexandrite Physical Properties
Tenacity
Not Available
  
Not Available
  
Solubility
Not Available
  
Not Available
  
Durability
Not Available
  
Not Available
  
Specific Gravity
3.49-3.57
  
3.69-3.81
  
Fracture
Subconchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
  
Not Available
  
Cleavage
[001] Perfect
  
1,1 ; 3,2.
  
Mohs Hardness
8
  
8.5
  
Chemical Composition
Al2SiO4(F,OH)2
  
BeAl 2 O 4
  
Topaz and Alexandrite Chemical Formula
While comparing Topaz and Alexandrite 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 Alexandrite chemical formula.
- Chemical formula of Topaz- Al2SiO4(F,OH)2
- Chemical formula of Alexandrite- BeAl 2 O 4
Topaz and Alexandrite Specific Gravity
Another important criteria for qualitative analysis of gemstones is Topaz and Alexandrite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Topaz and Alexandrite Optical Properties during the identification of gemstone. Specific gravity of Topaz is 3.69-3.81 whereas that of Alexandrite is 3.69-3.81.