Milk Opal and Black Opal Physical Properties
Tenacity
Not Available
  
Not Available
  
Solubility
Not Available
  
Not Available
  
Durability
Not Available
  
Not Available
  
Specific Gravity
1.98-2.50
  
1.97-2.22
  
Fracture
Conchoidal
  
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
  
Cleavage
Not Available
  
Not Available
  
Mohs Hardness
5.5-6.5
  
6-6.5
  
Chemical Composition
Not Available
  
SiO 2 + H 2OUlrich Henn and Claudio C.
  
Milk Opal and Black Opal Chemical Formula
While comparing Milk Opal and Black Opal 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 Milk Opal and Black Opal chemical formula.
>- Chemical formula of Black Opal- SiO 2 + H 2OUlrich Henn and Claudio C.
Milk Opal and Black Opal Specific Gravity
Another important criteria for qualitative analysis of gemstones is Milk Opal and Black Opal Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Milk Opal and Black Opal Optical Properties during the identification of gemstone. Specific gravity of Milk Opal is 1.97-2.22 whereas that of Black Opal is 1.97-2.22.