Zircon and Sillimanite Physical Properties
Tenacity
Brittle
  
Tough
  
Solubility
insoluble
  
Not Available
  
Durability
Not Available
  
Not Available
  
Specific Gravity
3.93-4.73
  
3.20-3.26
  
Fracture
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
  
Splintery
  
Cleavage
{110} and {111}
  
{010} perfect
  
Mohs Hardness
7.5
  
6-7.5
  
Chemical Composition
ZrSiO4
  
Al 2SiO 5Michael OâDonoghue , Gems, Sixth Edition (2006)
  
Zircon and Sillimanite Chemical Formula
While comparing Zircon and Sillimanite 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 Zircon and Sillimanite chemical formula.
- Chemical formula of Zircon- ZrSiO4
- Chemical formula of Sillimanite- Al 2SiO 5Michael OâDonoghue , Gems, Sixth Edition (2006)
Zircon and Sillimanite Specific Gravity
Another important criteria for qualitative analysis of gemstones is Zircon and Sillimanite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Zircon and Sillimanite Optical Properties during the identification of gemstone. Specific gravity of Zircon is 3.20-3.26 whereas that of Sillimanite is 3.20-3.26.