Corundum and Rock Crystal Physical Properties
Tenacity
Brittle
  
Not Available
  
Solubility
insoluble
  
Not Available
  
Durability
Not Available
  
Not Available
  
Specific Gravity
3.90-4.05
  
2.65
  
Fracture
Uneven, Uneven, Gems, Difficult, Fibrous
  
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
  
Cleavage
None – parting in 3 directions
  
Not Available
  
Mohs Hardness
9
  
7
  
Chemical Composition
Al 2O 3Arthur Thomas , Gemstones (2009)
  
SiO 2Walter Schumann , Gemstones of the world (2001)
  
Corundum and Rock Crystal Chemical Formula
While comparing Corundum and Rock Crystal 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 Corundum and Rock Crystal chemical formula.
- Chemical formula of Corundum- Al 2O 3Arthur Thomas , Gemstones (2009)
- Chemical formula of Rock Crystal- SiO 2Walter Schumann , Gemstones of the world (2001)
Corundum and Rock Crystal Specific Gravity
Another important criteria for qualitative analysis of gemstones is Corundum and Rock Crystal Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Corundum and Rock Crystal Optical Properties during the identification of gemstone. Specific gravity of Corundum is 2.65 whereas that of Rock Crystal is 2.65.